from the Arc'teryx website on care of goretex garments (the caution about liquid detergets does not apply to Nik-wax goretx cleaner, which is what I have used for years with excellent results):
>>Be sure to zip all zippers before you wash your jacket. You can wash your Gore-Tex in a regular washing machine, in warm (not hot) water, on a gentle cycle. Please use pure soap (which is best) or a mild powder detergent. Do not use Liquid detergents or ones that contain oil, or have fabric softeners in them (such as Woolite). Detergent interacts with the DWR finish and will interfere with the performance of the jacket if it is not totally rinsed out of the material. Run the garment through at least one rinse cycle and tumble dry on medium heat. For optimum performance you may also need to re-apply the DWR (durable water repellant) finish on your water-repellant garment from time to time. Do not dry clean or store when wet.
All of our shells are treated with a DWR (durable water repellent) finish that keeps the outer fabric from becoming saturated with moisture so that the breathable barrier can do its job. Over time, the DWR gets worn away, most common in areas of abrasion such as the sleeves and shoulders of a jacket, or the seat and knees of pants. This coating needs to be replenished approximately once per season, or more often if the piece gets a lot of use or washing. If water is no longer beading up on your shell, it is time to reproof.
To retreat your garment, use one of the widely available spray-on or wash-in DWR treatments for waterproof/breathable garments such as Nikwax, Grangers, or Revive-X (Recommended by W.L. Gore® & Associates). Wash-in treatments tend to be less effective than the spray treatments. Often, simply washing the garment, rinsing thoroughly and tumble-drying at a moderate heat for 30-40 minutes can revive the DWR. The heat application is an important element in activating the DWR properties of the treatment, and most of the treatments listed above recommend that some form of heat be applied to the garment after it is treated. Once you have successfully cleaned and refinished your shell, it should work as new again.