Chin Spoiler Sag Repair

The old chin spoiler has seen a few parking blocks and hours of wind resistance at interstate speeds and above. Its starting to form a gap between the top of the spoiler and the bottom of the bumper. The holes are getting a little rounded out and dont hold as tight as they used to. I know this must be common. What is everybody's go to fix for sinching it back up tight? I have a couple ideas but want to bounce it off Stangnet before going at it.

I was referring to the Mach chin spoiler. Thanks for the reply. I was pondering just putting a metal washer inside the bumper to serve as a reinforced hole for the plastic rivets. But screws, washers and nuts would really hold that thing on.