There is no reboot later option in MSL web GUI. Only reboot now or shutdown
How ever linux has a command to do just this
I found it on this web page
That doesnt work on Debian but this should web page
E.G sudo shutdown -r 14:10
Or if you would rather do it on a re-occuring schedule
try this web page for the crontab entries
Every six months = 0 0 1 */6 *
While logged in as root via putty (if you dont know how to get in to MSL via putty see my other post here
edit crontab by using command crontab -e
add a new line – 0 0 1 */6 * /sbin/shutdown -r now
The -r means reboot.