repotting or mounting C (Sophronitis) coccinea?

[Ioana]

I have 2 small C. Coccinea that I bought in clay pots with a tiny bit of sphagnum in the pot. They are growing in a vivarium (~95% humidity) but the roots have stopped growing and the pots look crowded.
I water twice to three times weekly (RO water w very dilute K-lite fertilizer, flush with pure RO about every 4 waterings). I don't know if salts are accumulating and preventing growth, or if this is a normal resting behavior.
I love these little Catts: these are the first that have grown well so far for me and I would really, really like to avoid killing them.
I'll soak them today, but after this, should I repot or mount? Should I wait for new root growth?
Thanks for any help!
Ioana