I would start by questioning why you think you want to do this. A well maintained computer system will run for months, stopping only for upgrades or other changes. I've seen a Confluence with an uptime approaching 18 months (Although I wouldn't recommend that, because the server running it really really should have been upgraded past a point where it needed a restart)
After you've solved the underlying problems, and come up with a good reason for a regular restart, I'd go with a crontab that simply does "systemctl stop confluence" and then the same with a start 5 minutes later during the quietest hour for your people. (4am on a Sunday is a good option, although as a support person, 9pm on a Friday actually works better - gives us a weekend to fix it if it fails)
