You gotta dry it out. Get a hairdryer, and blow it dry. Then get your flat iron and... Just kidding.
But seriously, pull your bulb, use a hairdryer to dry out the lens from the inside and check the seal on your bulbs headlights and signal. They may need to be replaced. If the doesn't work, you'll need to reseal the lens itself. Tape the clear lens up with blue painters tape and put it in the oven at 150* for about 5 minutes to soften the adhesive then you could add more adhesive around the lens and clamp together until it cools.