Search for this thread on the Families forum:
Post family Disney-theme night ideas HERE!
There's a ton of people on that thread with good ideas on different movies - no Frozen yet, but they're most likely to respond there since a lot of us are subscribed to the thread.
Make sure you post your ideas there too.
Here's a couple thoughts:
Dessert: shaved ice
Drink: served in a frosty mug, maybe a rootbeer float or something with disney ice cubes
Food: Since it's based off a Hans Christian Andersen tale, maybe Danish food like fish or an open faced sandwich.