Hi.
I had this happen to two of my torches in the past.
The first one was a LumaPower torch.
I thought no problem, I'll just reach for the superglue and fix it. Put the superglue on the edges of the dome and waited for it to stick.
Was it successful? Depends on how you look at it. The superglue indeed fogs over the dome, but now I have a reasonably good floody torch. There's always a bright side to everything !
The second torch was an LRI Proton Pro.
For this one, I used a silicone sealant that dries ultra clear. I simply put a blob of it directly onto the chip, positioned the dome back in place and have not had a problem with it since. The silicone has stayed crystal clear, there has been minimal effect on the beam pattern or output, and my Proton Pro is back in business.
Here is a link to the manufacturers website
http://www.selleys.com.au/Selleys-All-Clear/default.aspx.
Regards from the land down under.