To issue a new secret key for a service node, use node-reissue-secret-key operation. Use filter-id, filter-ip or filter-hostname to specify the target service node.

Request 

<packet>
  <extension>
    <call>
      <plesk-multi-server>
        <node-reissue-secret-key>
          <password>setup</password>
          <filter-ip>1.1.1.1</filter-ip>
        </node-reissue-secret-key>
      </plesk-multi-server>
    </call>
  </extension>
</packet>

Response 

<packet>
  <extension>
    <call>
      <result>
        <status>ok</status>
        <plesk-multi-server>
          <node-reissue-secret-key/>
        </plesk-multi-server>
      </result>
    </call>
  </extension>
</packet>