A New-Game+ feature (if you don't know what that is, it's basically an option you get when starting a new save that lets you do things you couldn't do the first time around, such as use your old stats and levels in an RPG) would extend replayability by a large factor. Here's a few ideas for options:
- Ant Selection - Choose the ants you start out with by spending royal jelly. You can choose any ant that can be built, but normally unplayable ants (such as the Counterpart Colony ants) will cost more than usual. Because this requires the player to have beaten the game at least once, there is no need to worry about balancing the Formicarium Challenges and such for any of the new choices.
- Keep Resources - Can be enabled to let you keep the resources from your previous save, possibly with one for each resource.