The transparent way is to join the new controllers to the old cluster, vol move everything, rehome the lifs, and evict the old controllers. Same SVM, new gear. Sounds like its too late for that though.
So what I'm laying out here only applies to a CIFS vserver. Disregard all of this if we aren't talking CIFS.
If you really want to rename your CIFS vserver from an AD perspective, you must record all of your share configuration, delete the cifs service, recreate the CIFS service with the new name, then repopulate your share configuration. You can plan/script all of that, but its somewhat involved. This blog post may be useful: https://whyistheinternetbroken.wordpress.com/2015/05/01/techusing-powershell-to-back-up-and-restore-cifs-shares-in-netapps-clustered-data-ontap/
Another option is to keep the old AD name, set a netbios alias on the vserver for the new name, add a DNS alias (CName), and set the service principal name (SetSPN) in AD. More touch points in AD, but you don't have to rebuild your shares.
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