Changing the target location of an already configured replication requires vSphere Replication to unconfigure and then reconfigure the replication.
All replication instances are lost and vSphere Replication performs an initial full sync to the new location for all virtual machine disks. If a replication seed was used for some of these disks, vSphere Replication uses the seed again.
If the source host goes offline after vSphere Replication unconfigures the replication, the virtual machine is not configured for replication.
The source host must remain online during the reconfiguration and stay online during the full sync period so that replication is in the OK state as it was prior to moving the disks to a different location. The sync can take a long time if there are no replication seeds.