I have removed mine before and stuck it again and it works fine. It is really hard to do. But what I did is I tried to keep the pad straight while pulling it off slowly. Otherwise, if you bend it while pulling it off, it could damage the wiring in it or something.
So I decided, if I have to do it again, I'm going to use something to help unstick the adhesive and then place it on a tile or something underneath the viv without sticking it directly to the tank.