If you run out of Raid Energy, there are two ways you can recharge. If you have Raid Energy Refills, you will be able to fill your Raid Energy.

If you don't have Raid Energy Refills or you have depleted your supply, you can spend Power Cores to buy more Energy.

Note: You don't have to spend any resources. Raid Energy fills automatically over time. You will receive 1Raid Energy every 14 minutes and 24 seconds.