I ended up deciding to repot it. The surface mold was even worse this morning, it was looking like algae was growing, and it didn't seem to be drying. It was so soaked, most of the soil fell away when I took the plant out. All the roots look great though, so I don't think there was any harm done by all the water and molds. It's now in a chunkier mix, with some extra space for those big roots to explore.
