Then again, maybe they were never that waterproof to begin with! I'd be wary about the spray-on sealer-like stuff for two reasons: (1) You don't actually want to have clothing be waterproof like a rubber glove since you do produce moisture and you do want to let it get out rather than freeze inside the glove and (2) perhaps the gunk would result in a slippery surface.
Since you're obviously the type of person who'll spend $50-75 to be out in the rain for four or five hours, there's no sense in telling you not to ski in that kind of weather: better buy some GoreTex.
But, to the point, I'd heard the stuff sold by the same guys who make the Tek-Wash(?) actually works (although I don't know about if it's a good idea to wash gloves or not).
I just used one of their other Nikwax products to re-spray my 7 year old ski pants and it seems to be working pretty well so far. For shoveling and brushing off the car I use a pair of soft fabric lined leather work gloves that I found at Home Depot for $4, but they are far from waterproof. If your gloves aren't made of goretex, you should think about getting some if you plan to stay dry.
Nik Wax works well to rejuvenate Goretex and similar fabrics.
Be careful what you wash goretex with. Liquid laundry detergent ruins the goretex, use powdered soap the milder the better such as Ivory. The fabric softners in liquid soap (or that you add) are what cause the problem with breathable fabrics and some treated fabrics. Washing also accelerates the ageing of the material because of the rinse and spin action.
Air drying is another way of extending the life of waterproof garments.
A great general purpose waterproofer is deck/concrete treatment stuff. My garage is in boxes (just moved) so there's no hope of digging out the label tonight, but I've found the Ace Hardware concoction to be excellent for most nylons & polyesters, plus a lifetime supply--a gallon--costs less than $20. Wouldn't know about it's goretex safety, but after all, it is a waterproofer, not waterbreather. Anyhow, discovered the stuff trying to save my old tent prior to an Alaskan trip. Brushed it on, let it dry, and it worked great through a whole week of Alaskan rain! Couldn't believe it. Now I give my old gloves a coating on the fabric side every preseason, along with some Snoseal on the leather, and they surprise me every year by surviving yet another season. A product called Shoe Goo works a lot better than duct tape for minor glove repairs, too, by the way.