Wilderness Reflex jacket - DWR treatment?

I've just today acquired a Wilderness jacket than my father purchased somewhere around 1994-1996. It is the Reflex material and hasn't seen a lot of use and has never been used with a pack, although the DWR has become non-existent I presume due to its age. Does anyone know the best method and/or product for refreshing the DWR on Reflex garments?