Follow the steps below.

1. Take a backup from your current/old appliance for safety if anything goes wrong. You can do that from the Operations Console. Navigate Maintenance > Backup and Restore > Backup Now.
2. Shut down one of your replicas and deploy a new replica, and attach it to the primary instance.
   1. You need to build the new replica as virtual machine or a hardware appliance in the new server or the new platform and better to use the same hostname and IP of the deleted replica if you don't want to apply any changes in the network configuration in general.
   2. When building the new replica you are going to deploy it on a base version for example (8.8) make sure to apply any needed patches to match it with the primary instance version after the replication is good.
3. After making sure that the replication is normal, and the new replica is up and running on the same version and patch as your primary, promote your replica with the option of Promotion for Maintenance to be the new primary.
   1. Do that from the replica's operations console > Deployment Configuration > Replica Promotion > Promote for maintenance.
4. Make sure that the promotion went smoothly, everything is working fine, and the services are up and running.
5. Shut down the other replicas if you have more to be replaced, the old primary is a replica now as well.
6. Redeploy all of them as new instances and attach them to your new primary.
7. If you want your primary to have its previous network configuration, promote the replica that was duplicated from it to be the primary at the end.