Sometimes conditions exist were you need to have database restarted immediately. You could always put up an alert and ask the user to restart the database. However, if you want to force the issue and take the decision out of the users' hands, use the OPEN DATA FILE command. When called with the current data file as the target, OPEN DATA FILE(Data file) closes the data file, quit and restart 4D with the current data file.
Note, any code in On Exit Database Methods and On Startup Database Methods will successively be called.