They will breed based on the amount of food given, as do most snails.

If you have too many you simply put less food in the tank and nature takes its course (survival of the fittest.) If you want more you don't simply feed more food, but a reasonable amount that will be eatten and not sit to rot.
Also if you get too many cherry shrimp going a lot of fish will view that as a nice food. (High in protein, kicks in the thrill of the hunt/chase instinct, and little risk of injuring your fish as it tries to eat it.)