I had a broken vertebrae and was wondering how likely am i to break it again?

That is really : Dependent on the mechanism that caused the fractures & your continued exposure to such environments ( extreme sports) as well as the underlying density of your bones which can be affected by diet, body weight, and underlying medical conditions. All bones heal & to original strengths, although some may be mechanically compromised if there is significant residual deformity leading to higher risk.

Hard to know: It's hard to determine as we do not know the injury you sustained to get the first fracture. Without knowing the trauma you had, bone density or medications you are on, it is difficult to predict.