...
Windows (Administrative Tools)
Click on the Services icon in the Administrative Tools section of the Windows Control Panel. Select the qubeSupervisor
service and right click to select Restart from the menu.
Windows (Command line)
From a command prompt:
C:> net stop qubesupervisor
C:> net start qubesupervisor
You can also restart the supervisor Supervisor via the GUI: "Administration > Supervisor > Stop", then then "Administration > Supervisor > Start"