Gosh I don't have a clue. Only answering cuz I didn't want you to think no one cares aboutyour post!
kathy

I have had pretty good luck RE-securing thingys (technical term there), with my low temp glue gun. It is pretty tiny and it's "nose" fits in small spots to glue things.
You could also use a drop of glue on the berry and put it in place with tweezers. HTH

By tiny, I'm guessing smaller than bb's.

Glue often eats styrofoam. I'd go to Wal-Mart or one of the craft stores and look in the spray paint section for clear spray paint. Spray the a test ball a section at a time where the paint isn't dripping off, but isn't just a fine mist either. See if that sticks. If nothing else, it might provide enough coating until you could modge podge a layer over it without melting the styrofoam.

I'm reading this to see what solutions are offered too. I had bought some candle rings at Christmas and the berries were dropping off like crazy too. Luvs