A beta customer recently asked about the default refresh interval for VMM - after what amount of time should he see changes he's made on the host reflected in the VMM administrator console? By default the beta 2 interval for this is 30 minutes, but you can run the PS commands below to force a refresh and ensure the changes you made are "sticking":

$c = get-vmmserver <scvmmservername>
$h = get-vmhost <name>
$h | refresh-vmhost