Their feet is destroyed, so I think they can just circulate the paste from the pool into their body and excrete older one right into the pool too. Remirya will just suck from above their head, which is probably where the yukkuri is regulating the better paste.
There doesn't seem to be much story telling about how predator yukkuri spend winter isn't it.
Maybe it's just a way to play with it's food. It's an interesting way to torture them even if it doesn't help preserve them.
Predator's way of passing the winter
Pile the food with broken feet into shallow pool of paste. This way they won't die and got eaten until the end of winter.