I have done a restore of the setup and configuration. De replication tasks are back.
I also cleared the metadata on the primary (failed DSS) en select Volume destination.

The last steps (correct me if i'am wrong) is: starting replication services on the primary DSS and select the sync button in the backup unit (wich hold the souce volume)
When the sync is completed i can do a fallback so that de primary is the active node en de backup DSS is the passive node.

Is that correct?

Thanks for the answers.