The pergo boards are manufactured in a press that applies several thousand pounds of pressure per square inch, not to mention heat, and a lot of other things. If the board got wet and swelled, it's a lot like those promotional wafers with printing on them that you get, and when you get them wet, they turn into a sponge. Ever tried to make it turn back into a wafer?
So, you are probably going to have to replace the board, which is a neat trick because the floor is a tongue and groove deal. You can DIY, which I think is risky, or you can hire a local professional who advertises pergo and ask them to do the repair. In either case, do get a price on the pro job so you can make an intelligent decision.
When Pergo first came out, I thought it was pretty neat stuff. Lately, I think I've changed my mind.