First, you must determine the cause of the breakage. Are your ponytails too tight? Is your hair over processed? To what extent is your hair damaged? And what will change about your day to day routine to keep your hair from getting damaged again once its been repaired or cut? Generally speaking, once hair is truly broken, there is no good way to repair it and so it is best to cut it into a healthy state and move forward from there.
Good nutrition and scalp circulation are vital to healthy hair as is using professional grade products that are pH balanced for your hair. Yes, they are more expensive but they are also more concentrated, thereby lasting you longer. Invest in products that will bring hydration and elasticity back to your hair. Get your hair trimmed regularly every 6 weeks- in order to remove your split ends. As long as your ends are split, you will be unable to grow any length because they will always break off.