Crontab and a bash script can sort that out for you.
If you don't know how, search for it and read up on how to set that up - there's a lot of examples around.
And if this is for a modded server - you might want to restart more often than 1 time per day, every 4-6 hours depending on the pack, you can do a count down via the bash script so there's messages sent from the server in-game for players to see.