I too have a Jade plant that came from my grandmother. AS I remember the story, it was something she sent away for from a cereal box. Don't really know if that is true or not, just the story I remember. At any rate, I did something stupid, and mine got to a point where it needed something done to it, and I called Ralph Snodsmith on the Garden Hot line (this was years ago) He said to cut the top off where it was not yet harmed and start a new plant. That is what I did and it has been going great every since. Hope that works for you.
Carol