Thanks for your inquiry.
You will need to unlock these functions by leveling up your bases.
* The refill function can be unlocked at level 2. Refill can heal injured troops.
* The expand function can be unlocked at level 3 with the expand limit at level 2.
* Every 2 building upgrades increases your Troop's Level Limit by 1. That's to say, you can expand your troops to level 2 in a level 3 base while you can expand your troops to level 4 in a level 7 base.
Side note: the maximum level of the bases is 20.