I do not run MLD and not on a Raspi - but VDR has a feature to run commands, which can be stored in the "commands.conf" ... So depending on the upstart/systemd or whatever init system is used, you should be able to trigger a restart by just calling the command.
Or sending it to the background as an adhoc cron task (if e.g. "at" is installed).
Search the wiki or the forum, there is plenty "old" entries on this if I remember correctly.