Clean Gore-Tex fabric will remain waterproof because of the very fine weave fabric. Layered rain gear has an outer layer that is not the Gore-Tex fabric and that is what you think has lost it repellant quality. To restore the outer layer, the product recommended by Gore-Tex garments is called ReviveX. That product, when applied correctly, will make water bead on the surface again as long it remains clean. Dirt, oil, grease, sunscreen, etc on the outer layer and inner layer of Gore-Tex fabric will allow moisture to penetrate as it acts as a wick.