Unlock Flower Cat:
At the 'Cat Base' menu repeatedly drag the handle of the door to the right so that it opens and you see red-eyed cats and hear meowing. After doing this a few times a message will appear on screen informing you that you have unlocked Flower Cat. Flower Cat can be accessed by going to 'Special Cats', this cat is good at attacking and has a slight chance of stopping black enemies.
Restore Cat Energy:
If you do not want to wait for Cat Energy to be restored so you can play again you can refill it instantly by advancing the time on your device (remember to set it back again afterwards).