There has never been a wholesale repowering of the mutant victims. Unless it's shown otherwise, everybody that lost their powers is still depowered. Those repowered are the exceptions to the rule. IMO, they should just repower everyone.
I thought they were all repowered at the end of AvX 12 by Hope Summers?
All that accomplished was that new mutants didn't need to be activated/prepped by Hope.
For a while, from Second Coming to AVX, Hope needed to physically confront new mutants, else they would die horrifically. That's what Generation Hope was all about.
AVX's outcome gave us new mutants that didn't need this assistance, like Nature Girl, Eye Boy, and Sprite. Everyone else remained depowered.