When I wanted one of mine to split, I'd feed heavily for a couple of days then do a major water change. Usually within 48 hours I'd have a new Rose in the tank...
BTA's are rock anemones, and as such, I always feed much more shrimp than I did silversides. I just don't know how many freshwater fish they get in nature...
Besides, being natural rock dwellers, I'm sure they get lots of nice meaty crustaceans, and mine always macked it up...gotta be careful how big of pieces you give them however. I always cut the anemone foods into chunks no bigger than 1/4" cubes. Smaller pieces are MUCH easier for them to digest.