Ultraheat RV has a list of recommended adhesives to reattach the pads if needed:
https://www.ultraheat.com/approved-adhesives
My original heating pads installed by Jayco were falling off from day one. I tried to clean it up and secure the edges with the black Gorilla duct tape. That only lasted about a year for me. Ultimately I replaced the black and grey pads with their combination 120v Ac/12v DC pads. When I installed the new ones, I did cover all of the edges with Eternabond tape. Rain, snow, and many miles later they are stuck just fine.
The heated tank pads serve a purpose for our family (we use our unit in the winter too) but only if you go to the time and expense to heat/insulate ALL of the exposed pipes underneath the rig. I have done it on our last 3 units - Starcraft AR-1, Jayfeather X213, and now the Greyhawk. Worth it to me, but obviously not for many people.
-Doug