If it the attachment point at sail track. and just worn.
Take rollout out of it's track.
Down to Sailmaker.Upholsterer. and get him to sew another bolt rope into it.
Will lose you around 4 inches of "out" on your sail track.
If that a problem. Get him to make up a bolt rope in material, complete.
They cut off worn material from roll out and sew that piece onto end of the thing.
If only part worn. You can buy "self adhesive" materials to suit.
Cut to length. and apply
Preferably with roll out out of it's track.(quite easy to do with two and a coupla steps if a tall van")
so you can apply "weight\s?, to that area.
If you "stitch a patch). as said. Beeswax or clear silicon is best afterwards.
I had a "tree scrub" of around 15in at rear end of this one when bought it (pre us)
I just got some liquid "rubber ducky" adhesive I had from the old days
and brushed it on. Done. Set clear, smooth and super flexible.