You can migrate VMAN database from VMAN appliance to another one. But the destination must be VMAN appliance too. Further details are at VMAN Admin guide, section "Migrating from a Windows installation to a virtual appliance" section. It's not possible to move VMAN application itself to clean virtual machine.
If you just need to extend disk size or change any other system settings then contact Support team.
Hope it will help you. If not, please describe your problem in details.