From GPS World:

Dubbed the Architecture Evolution Plan (AEP), the upgrade will replace the Air Force's entire GPS master control station, including both software and hardware, some of which dates back to GPS's inception in the 1970s. The upgrade will, among other things, prepare the master control station to work with the latest generation of Block IIF satellites when they go into orbit, according to the Air Force.

This is due in the second week of September. They seem confident that "users of the system should not notice the transition".
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