Hello.
Recently, I have become obsessed with these primulina and gesneriads overall (again)

Any tips on caring/repotting/water/soil for them?

I only have a year of experience with Primulina spp., but they do respond well to fertilizer and watering. I'm not used to watering my plants as often as they seem to like. But they do like very porous soil. Being from a wet environments, I assume they prefer acid soil. Now that I have a metal roof, it is so much easier to collect rain water. Makes a big difference compared to the high pH city water. And especially for cactus..... who woulda thought?

An update on Primulina yungfuensis: it bucks the trend and for me, doesn't like so much water. Now that I have learned, I water it about half as much as my other primulinas.

Interesting!