Sometimes no matter what that will happen. It's hot and humid, then cools for the night. that humid air gets sucked into the light as it cools down, then that humidity condenses. Next day, it heats up and air expands but that little puddle of water doesn't quite go away. It cools down the following night, more humid air gets sucked in, it cools and condenses a bit more. Repeat and soon you got a lot of water in that lens and any time it's sunny out, it's trying to evaporate now, but getting caught on the inner lens.
If you can find the vent hole, turn the bulb so its hole down, tap so the water goes down there, get a vaccuum and suck on it to get it out. Otherwise heat it to about 130 ish, and let it evaporate off / out of the thing.
That's a lot of water though, something is cracked somewhere I bet. A welded seam is open or something letting water seep in there id bet.
Another problem, that humidity in there WILL corrode the electronic parts and that will fail, and sadly it won't take very long either for that to happen I am betting.
Aaron