I've used wash-in Nikwax on my earlier shells. I also wash them with the dedicated detergents. It does help, but in this case I believe it was the seams that started to leak.

BTW, GoreTex advise AGAINST wash-in water repellents, saying they can have adverse effects on breathability. Better use the kind you apply on the outside only, at least with GoreTex membranes.

--J