Re waterproofing/seamsealing

I've got a Ridgeline coat that i got in a package deal with duck shooting license .............quite a few year ago. After about 3 years, the seam sealing inside started peeling off. Started around the zip so wasn't to concerned, but now it's peeling off across the shoulders and back.
Question is can they be redone, or is there a treatment that could be sprayed/ painted on the stitching. Will a waterproofing spray, if sprayed thick enough on the stitching provide adequate protection.
The coat itself is still in good nick, just leaks abit now