Dogpack,
Your plant looks like it has powdery mildew. I agree about changing the soil and cutting it back for a second chance. Also, put it in a clay pot instead of a plastic pot, don't let it sit in water and make sure it is getting air circulation and bright light. When the soil dries out, give it a good drink and empty the drainage dish after a couple of hours. I have kalanchoes doing well in regular Miracle-gro soil but I amended it with perlite and vermiculite somewhere like one third to a half in volume. I'm not saying not to use cactus soil. It is a good option.
Once the weather gets warmer, bring it outside in a shady spot. Do not expose it to direct sun until after a couple of weeks. If it makes it that long, it should recover completely outside.
Or just get a new one because they are pretty cheap.
