I had water in my rear taillight. I drilled a small hole in the bottom, and then used a compressor to blow the water out from the inside (low psi). I don't notice the hole unless I look for it. I might change the lens one day if I get motivated.
This is that middle reflector right? I don't have one of those, but you should be able to do something similar.
If the reflector is completely sealed then you could probably do two small holes in the back, or bottom. One to blow air through, and one for the water to come out. When it is dry, then seal the holes (and where ever the water came in at) with something water resistant ("Goop" would probably work.)
