I sprung this on my wife on our trip last week. She was a good sport (she accepted my insanity long ago). It's a short, cute ceremony at the Garden Grill. Only read below if you want to be spoiled.
* Spoilers Below *
* Serious Spoilers, and I'm not kidding! *
* Spoilers ... Read at your own risk! *
Okay, here's the deal. You mention you want to do the Rehitchin' when you make your PS or when you check-in at the Garden Grill. Sometime during the meal, the server will come to your table and say something about you requesting a rehitchin' ceremony. At that point, he'll ask you and your spouse to stand and may ask you how many years you've been married. He'll then announce to anyone within earshot that "we've got a celebration here."
He'll take you through the "I Do"s, then ask you to kiss while he counts to 100 (our guy counted 1 - 10, then 20 - 100 by 10s). We were then presented with a cool certificate, indicating we'd been rehitched. No extra charge!
It's good fun!