Hi,
vSphere Replication is an extension to vCenter Server and relies on it. It requires vCenter Server on the target site to be up and running in order to invoke Recovery for a replicated VM. You can configure replication for the vCenter Sever VM to be replicated on a target site just the way you configure replication for any other VM from your inventory (assuming that you are using different source and target sites). However, after recovery you will need to adjust correct IP settings as vSphere Replication recovers the VM with network devices disconnected. If you are using single site setup then you require that the vCenter Server up and running in order to invoke Recovery. There is no supported way to recover the replica without the vCenter Server in a single-site configuration. Hope this helps