My guess is that Xavier hasn't trained another telepath to use the new cerebro, and that Jean will have to step up and resurrect him. In one of the data pages in HOX/POX, we can infer that Xavier hasn't trained another telepath to do it because it says eventually a highly skilled team of telepaths would need to be trained to assist Xavier in all of the resurrections (it was stated there were too many that needed to be brought back for Xavier to do by himself).