I think most manufacturers sell replacement tubes. We own a "Jolly Boat" rib
that utilizes "Caribe" tubes on a different fiberglass hull
The difficulty is finding someone to install them. I don't know what is involved for do-it-yourselfers. I doubt it's brain surgery but I don't know if I would want to tackle it without some instruction.
Check with your dealer or a shop that specializes in inflatable