How do I increase the orange bar on Dantes Inferno for Xbox360?

I’m currently playing Dantes Infreno on Xbox 360 and at the bottom of the screen there is an “ability” where if you hold the left bumper button and right bumper button at the same time you burst into flames. The bar at the bottom of the screen for this is orange, when its full you can use this ability. My question is how do you increase the length of the “orange bar”? I’ve seen on a few walk through videos that they were double the size of mine and I can not figure out how to make mine longer.