You can try putting it in a hot oven, that has been turned off, for a few minutes. Then use a spakle knife to seperate the lens. If you just want to re-seal it, you're probably better off just running a bead of silicon all the way around and smoothing it with your finger. The problem with pulling them apart and resealing, is that you can't use silicon because it melts at a much higher temp then the plastic of the lights do. If you don't seal it correctly the first time you try, you'll never be able to get them apart again. The sealant that the factory uses is very hard to find, you can't get it at pep boys or a place like that, and it obviously melts at a much lower temp. I thnk clear silicon around the seam is your best bet, and much easier to do.