if you dont want to install anything to restart domoticz when it's crash. you can put crontab to check it with bash script like this
put this on your cront :
*/1 * * * * sudo /opt/Domoticz/scripts/online_check.sh 2>&1 >> /dev/null
and this is online_check.sh
#!/bin/bash
#Title check_domoticz_online.sh
# check domoticz
sudo service domoticz.sh status
# if not found - equals to 1, start it
if [ $? -eq 1 ]
then
sudo service domoticz.sh restart
else
echo "Domoticz running - do nothing"
fi