Give it as much sun as possible (in stages), water some, let dry, water some more with soe diluted fertilizer, let dry, repot and water some more.

You shouldn't let it go totally dry in the winter. A little water would be beneficial.

There are numerous posts here concerning Crassula ovata.

I don't understand the "don't water" mentality at all. I know there are some things that need minimal water in winter, but growing in the warm conditions of a home, you can't let any plant stay completely dry all winter. I water my Jades at least once a month in the winter months, more if we have a lot of sunny days.

I think your best bet is to water it well and, as Jeff said, put it outside (if you haven't already) and acclimate it to sun over a few weeks. But I'd keep it in a slightly shady spot until it plumps up. Don't let it get too dry. (I will add a caveat to this advice - if you live in a very hot and very humid place like the gulf coast, you have to be more cautious about watering...)

Good luck with your Jade. It will probably bounce back just fine. They're almost indestructible!

Denise in Omaha

I have lots of varieties of Jade some like trees and others in clay pots. You're lucky to still have green. Jade is hard to kill but I would pull it out of that pot and check the roots which might be root bound or have a disease like one of my succulants had the other day which was looking stressed so I loosened the roots and washed and rinsed that pot well with Dawn and replaced the soil and that little guy is so happy. The drainage holes which I never thought to check was all closed with gunk. Don't be afraid to cut back the spent branches cause they'll grow back quickly. Jade grows in any light, I have suckers growing well under other bushes. It's like a weed here. I never overwater but I bet a huge weather change not like here in San Diego can cause the dry out but I put my money on the inside of the plant..

A deep soaking every 2 weeks is the best advice I could give you...In summer or winter.Give it some Osmocote so when you do water it'll trigger the time release and you'll have this huge thing blooming like you wouldn't believe in the late winter.