One approach might be to split all nodes of the cluster into two server-groups and update the group. If you need to bring down all servers you might use two different domains.
Yes, I think you will have to create a new server group with new application deployed and new cluster configuration (different multicast port or address). Then you will shutdown server from old group and move it to new group and start it up as part of the new cluster and repeat for each server.
Depending what the upgrade to the application is you need to think about database updates, node-to-node/remote invocations, session object compatibility, etc. The above solution only covers the application update itself and session object compatibility.