1. Log into Central -> Maintance -> Unassign group for that VC or Select ALL GROUP agains that VC.
2. Add VC back to Central. It will come as unprovisioned.
3. Now click on unprovisioned VC and it will give you option to 1) add to existing group by overwriting existing config or 2) improt config to new group.
4. Select 2nd option and you are all set.