So my croton petra is a more recent member of my collection and it's been struggling a bit. My sweetie got it in late December 2017, had it repotted in the store (85% soil, 15% perlite), and then gave it a bit of a wild ride home through a snowstorm while it was covered in a plastic bag. It, of course, dropped a bunch of leaves in the initial culture shock transition but has for the most part settled down, still losing about 1 leaf a week. The leaves shrivel completely before falling off, which I'm pretty certain is a humidity issue what with it being winter and the heat running. I might also be underwatering so far, just really afraid of rotting out another beautiful plant (especially since I've never seen it's root system and can't vouch for the quality of the repot at the store). The pot's pretty large (glazed ceramic with attached saucer), but I might cave and put in a humidity tray soon. I've been misting the leaves, but that's more for my peace of mind than actually helpful, I think. The pot holds 4 croton petra plants (each about 2 feet tall), which I'd like to keep together since my sweetie prefers the look of it.

I know I'm not providing enough light in the partially obstructed east/northeast window (but it's literally my sunniest spot). The leaves are definitely greener than when it first came home, but the croton still looks generally healthy, still adapting to the new environment. Most of the lost leaves have been predominantly red, large, and already damaged in some way. I have plans to acclimate it to the summer sun once it's warm enough to leave it out overnight on the porch and really give the colors a chance to come back for the season.

In the past couple weeks, the cat got into the room with the croton three times and dug it up, kicking dirt everywhere, most recently this week. For right now, I've been trying to let it dry out a bit before attempting a repot, since half the dirt's gone anyway and I don't have any more soil in the house at the moment. Heaps of perlite, but no soil.

Anyway, I just wanted to see if anyone had some advice on what sort of medium would be best to help my croton thrive? Would it be alright if I buried the stems deeper than they are now, considering the leaf drop we've already experienced? When I repot, would it be a good idea to get the roots completely bare and replace all the soil (no idea if the cat peed in there or not)? Should I untangle the 4 plants' root systems while replacing the medium? Should I water it thoroughly right after the repot or let it rest for a couple days?

Really appreciate any advice you could send my way. I'm still pretty new to houseplants (less than a year) and have gotten so much good info through these forums. Just nervous about this one since my sweetie loves it so!