You could glue back all parts which have become unglued if you want to, but cost will be pricey if sent to a reputed boat shop. Another story if doing the work by yourself if you're skilled and know how to re glue well. Will need tons of work, patience besides good quality 2 part pvc glue, correct cleaning materials and appropriate temp while working at it.
On a sib the only part that can't be repaired is the fabric istself, once dried, cracked, pourous, delaminated, KO, it's shot forever and ever.
Btw, how old is that sib ?