When considering repairing a broken double pane window it is important to know that most double pane windows are factory sealed, meaning you cannot repair the window without losing its insulation benefits. Some of the problems that can lead to need of window repair are moisture in between the lites as well as broken inner glass. These problems cannot be easily fixed.
For instance, if moisture is entering between the lites your seal has broken and there is nothing you can do to fix it, the seal has failed and the desiccant has reached its saturation point. After the seal has failed you do not have to replace the whole sash, what you can do is replace the Insulating Glass Unit for a much cheaper cost.
Broken glass on the other hand means that you will have to replace the whole window. The replaced glass will no longer be factory sealed making it only a single pane window.
Before fixing any window it is important to find out who made the window. Contact them and check your warranties, they can also give suggestions on ways to repair if possible.