1)restore DWR - wash a lotm, dry it hot, iron and ReviveX
2)seam seal any holes or places where seamtape has come adrift
1) should help water repellency. 2) should cover any leakage or waterproofness issues.
Beyond that yer fucked. BUT, a non waterproof Gore shewll can be a useful piece. I have an old Arcteryx tester jacet I picked up for $20 when I worked there. It has no DWR anymore and even Revivex restores it for like 5 min. It had a hole I patched with seamsealer. Its a total beater shell and I use it for iceclimbing and wet alpine chimneys in the rain secure in the knowledge I'd probably get damp anyways no matter what I wear and this way I don't trash a nice new jacket doing it.