How about a "read-in" party, like a "sleep in" called "Snuggle up with a book day." Everyone comes in jammies to school with a favorite stuffed animal friend to read to. Parents or other favorite grown ups are invited, and everyone just snuggles in with their favorite "old friend" books... There could be a pancake breakfast theme with help from the jammie clad volunteers, if you wanted to include food... But for many, just the special cozy time with reading is enough! Special grownups from around the school love to be invited in to these parties, to visit, to snuggle with a book, or to read to the class in their own jammies!
Good luck and tell the kids congratulations for me (: