If you act fast, epoxy takes weeks to reach it full stone hardness. Heat will temporarly soften hardend epoxy. I would use the clamping method that Shawn has described. Maybe add come localized pressure in the center where it's bowed up.

I think however, that you'll have to drill a small hole in the veneer and inject in some fresh epoxy mix. because I believe it will just pop up again without doing that.