If you previously disabled system restore through the Group Policy Editor,
the option to start it again does not show in the System Properties.
You can re-enable it again by:
Run the Group Policy Editor (gpedit.msc)
Go to Computer Configuration / Administrative Templates / System / System Restore
Set Turn off System Restore and Turn off Configuration to Disable
Right click on My Computer
Go to Services and Applications / Services
Scroll down to System Restore Service
Set it for Automatic
Click on the Start button to start the service
Close down this window
Go back to the Group Policy Editor and configure both to Not configured
Now when you right click on My Computer, there should be a tab for System Restore and you can configure how much space will be used.