The map can be kept, just go to new chunks for jungles.
Why is the map changing next week? Can't it wait until 1.2 so everything syncs up, instead of 1.2 coming out like a week or two later and everyone being like "We JUST got reestablished, so no, we won't have new stuff yet."
Oh God damn it, the new map is made in 1.1. It won't have Jungles or other new stuff.