*UPDATE BY STORMZILLA: Aaron Starheart and Heather Raven have mentioned a good plan. Switch your pets to your alts, they uped the energy on lower level characters so, for example, my level 40 alt has 60 energy. Thats more then enough to train a pet to adult if you have the snacks. (Trust me, I trained a pet to Adult in about an hour, with the right kind of snacks it can be done).
When they reach the desired the pet level then you can transfer them back to your main. (Best to do this when your main has lower energy so its not too much of a waste). END OF UPDATE BY STORMZILLA*