Its so simple.Just change your device's date forward!Please note that if you get caught,you will be banned for how much you skipped ahead.
Shut down the app, and turn it back on after an hour, you will find your energy full.
Increased Energy Renewal
Your energy guage renews over time during gameplay but you can do the following if you need to fill it up faster. If you turn off the the game for 30-60 minutes your energy gauge will be full when you power things back up.