I just wanted to create a thread where we could document what we all know about the easiest, fastest load-free spots to respawn each of the ixupi, and potentially document our research into finding better locations/methods for forcing them to respawn. I'll list what I know here, and if anybody wants to fill in some of the gaps in my knowledge or post as better locations and/or back-up strats are found, we can just work on making this a more comprehensive source of info.

First things first, in case any new runners are reading this: you can tell when an ixupi spawns because the music changes when you are a few screens away. The music has the same melody for every room in the game, but it will be played with the same instruments as whatever the normal music is for that room. Once you know that there is a musical cue and you recognize the song, you'll be able to tell when an ixupi's nearby without having to go in for a close-up on its exhibit. Once you are one screen away from the spaw location, the ixupi will also start making noises appropriate for its element, e.g. flowing water, scraping metal, tinkling crystal.

So, let's talk locations...

Ash: Always spawns in the fireplace in Windlenot's office, and his pot/lid are always in the same locations, so there is zero need to force a respawn. This should always be your first ixupi unless there is some huge shake-up in routing strategy some day.

Cloth: Fixed location guarding a pot piece in the utility room between the planetarium and the werewolf room. Gamebop says there is a respawn location in the Egypt room on the screen with the first Anubis statue, but I haven't been able to make this work or had a scenario where it would be more convenient - am interested in seeing more info on this in case my cloth pot comes together after opening the Egyptian tomb, though.

Crystal: Chandelier in the foyer respawns when you face the door to the tar pit/giant eagle's nest/unicorn room. You do not have to open the door and you do not need to load new music, so this is a nice, fast spawn. There is probably also a way to make the crystal ixupi respawn in the Mysteries of the Deep/Atlantis room without loading, but it's seriously two rooms away from the foyer, so I think there would be very little utility in forcing a respawn there.

Lightning: Always spawns at the underground generator at the end of the game, no respawn needed.

Metal: So far, the best respawn I know is the film canisters in the projection room, which respawns by the time you get to the bottom of the stairs back to the theater. This is a lot of clicks and involves load time at the door to the projector.

I once had the unicorn in the eagle's nest room despawn when I climbed the ladder up to the nest, but I have not been able to force it to respawn. If anybody wants to do some science, there is science to be done.

I'm also curious whether the suit of armor in Windlenot's bedroom has a respawn point, because that would be helpful in 100%.

Sand: Mysteries of the Deep/Atlantis room ixupi respawns at the bottom of the stairs to the subterranean maze. I always go all the way to the door because I don't know exactly which screen the respawn happens at, but I'd be interested in hearing if anybody already knows or wants to do some science on this one. There is also a sand spawn location in the plant room where you get the ash pot, but you never need to go back to that room and the clicks to get to the Atlantis room are easier, so I'm pretty sure the sandcastle is all you need.

Tar: Fixed location at the end of the subterranean maze. Similar to the cloth location, I've never really had a reason to do science on the other tar location, and this one guards a pot piece, so I haven't seen a need to force a respawn on the eagle's nest room location, but if someone wants to do science for the sake of science, feel free to fill us in on any info on respawning the second location.

Water: Does not seem to be a load-free spawn location for the fountain ixupi, and turning off/on the fountain does not force a respawn to my knowledge. I've had exceptionally good luck with this guy spawning in the utility room by the werewolf exhibit, so I'm not sure exactly where the respawn is on him. Please fill me in if you know more.

Wax: Candles in the library have a respawn location in the secret passage behind the bookshelf. Just go left in the secret passage, face the wall opposite the elevator, then head back into the library and listen for the ixupi theme.

The wax snake in the Anansi spider room has a spawn location in the hallway past the werewolf exhibit, between the utility room and the stairs up to the planetarium. This has my vote for best respawn location in the game, because it's the same as the one for...

Wood: ... the pallet against the wall in the room between the Anansi spider room and the werewolf exhibit (which, according to the blueprints, is the Myths and Legends room). As with the wax snake above, the respawn location is in the hallway on the other side of the werewolf exhibit.

Wood also has spawn locations in the bone puzzle room (in the opposite corner from that puzzle), the gods and religious items room (right by the entrance from the shaman room), and the pallet by the horse puzzle on the way to the fortune teller, but I've done almost no research into respawn points for these, so I'm curious if anyone knows more.

That's everything I know. Please add anything else you know or call me out if I've given any misinformation.