I had the same problem. Park the car so that it is level. Find the lowest point of the lens and drill the smallest hole that you can. We used to do this on the outside equipment to let the water drain out.
Also on the base of the bulb, putting some dielectric past will help prevent water getting into the lens to start with.
When changing the bulb on my Cobalt, I also must have cracked the lens, and so far I have just left it. To much bother right now. However I also had a problem with the Beams burning out. I put some Rat Shack 6 Amp diodes in series with the lamps to drop the voltage 0.6 volts. This will help the lamps last a little longer.