Hydropool insulation...they plastic shrink wrap the spas plumbing then run a layer of reflective bubble wrap around that then also add a layer of the bubble wrap around the walls and floor. Now to get at a leaking jet body you have to cut through each layer and peel it open and repair. Then when finished you have to try and pull each layer back into place and tape it back together as best you can...if you remembered to bring the tape.
I would likely just tape on a new section of insulation over the top, maybe even staple/attach it to studs and tape. No more or less labor than re-foaming or whatever scheme.
