Thank you for your help, but I don't want cgminer to restart, I want the whole miner to reboot. Isn't there a linux command for rebooting with a timer like "shutdown -p 300" but then for rebooting?
EDIT: I got it, the command is reboot -d [SECONDS], so you could type in the command in system > startup so the command will be executed at startup and will repeat everytime after boot!
Edit crontab via SSH like in the thread linked or WebUI via
System ->
Scheduled Tasks, and to reboot every day you'd add:
0 23 * * * /sbin/shutdown -rebootto reboot at 11 pm every day (you change the hour to suit).