how do you know you have a fallen bladder? did a doctor diagnose that, or is that a diagnosis you arrived at based on your symptoms?
there are exercises specifically for bladder problems; i remember i took a yoga class once where the teacher concentrated on them. they involved having the legs spread apart and doing squats like that; i don't remember the whole thing, or the exact exercise. their aim was to strengthen the pelvic muscles. then of course there are the more well known kegel exercises http://healthlink.mcw.edu/article/922988755.html