Dash gauge "welding"

Dear FABO,
How do I re-weld these gauge lenses back into place? I have an original plastic dash that has had new chroming done to it and I'm trying to figure out how to get the lenses/turn signal lenses etc glued back into place. The little titties have been melted away during dis-assembly, and they must have a way of re-assembly or they wouldn't have gone through the trouble of re- chroming the plastic. ...no?

Thanks FABO!