You can upgrade your VBA but take in mind you cannot configure new policies:
EMC strongly recommends upgrading the NetWorker server and storage node to NetWorker 9.2 and using the latest available VMware Backup Appliance . NetWorker 9.2 does not feature a new version of the VMware Backup Appliance but supports the OVA and proxy version compatible with Networker 9.0 and 9.0.1. You cannot create a new policy for VMware Backup Appliance in NetWorker 9.2. You can only modify existing VMware Backup Appliance policies. For the creation of new policies, use the vProxy appliance.
You need to deploy NVP for VMware protection with Networker 9.2. You can deploy NVP and configurate all VMware backups with NVP and disable VBA backups. You will need to keep VBA for recovery purposes (NVP and VBA backups are not compatibles).