I would contact your VAR and ask them to reset that license so you can re-activate it. even if you are not on subscription they should help
You will need to contact your VAR. It seems that your computer ID may have changed during the update so you can no longer activate that particular serial number (SOLIDWORKS sees it as a new computer). When upgrading in the future, it is recommeneded to go to help> Deactivate Licenses... and follow the steps their to ensure that your license wont be held up in limbo.
Your VAR should be able to deactivate the license and reactivate it.
As an alternative (if you still have your install disc), run the Activation Wizard found at "swactwizard\Activation Wizard.msi" on the DVD.