I had two jade plants that both got powdery mildew and were slowly dying. One was my mother-in-law's and the other one was my mother's so I didn't want to lose them completely.
Jade plants are wonderfully hardy. You can simply stick a leaf or branch in a pot and it will root without any help at all! To re-pot a jade, get a pot a little bigger than the one it is currently in, put a little bit of fresh soil on the bottom, tap out the existing plant and set it in the new pot on top of the new soil. Then carefully add new soil all around the edge, packing it in some with your fingers. Then water lightly, and you should be good to go.