How can I have more energy when dancing?

Sounds like you need more stamina and endurance. This was my exact problem, but with other styles of dance too. I suggest starting to go running or at least jogging. I even jump rope and do lots of jumping jacks. Make sure to eat healthy energetic foods and keep hydrated. Over a period of time you're definitly going to start seeing results like i did. And as weird as this sounds, I plan my breathing with my dance. As in, there may be certain pauses or easy steps in the choreography allowing me to take a deep breath and regain the energy.