you can A. pull it out really soap the seal up and reinstall Or B. my Favrite go to your local auto store get beutal caulking. (napa normally has it)put either a thin stick and pull the seal out a little while you caulk right into the gap. normally works best if you have three hands but if you dont cut the very end of the tip off. so you have a small openning, use that like it was the stick and just shove in the gap keep it in the gap while you caulk all the way around.
I like using beutal because it never really hardens and if your windsheild leaks again you can add more or just move whats already there around a little.
