Click the drop-down arrow on the right hand side of the Quick Access Toolbar.
Select 'More Commands...' from the drop-down menu.
Select 'Commands Not in the Ribbon' from the 'Choose commands from' drop-down.
Scroll down the list of commands until you see 'Print Preview Full Screen'.
Select this command and click 'Add >>'.
You now have a new button on the Quick Access Toolbar that will activate the 'old' print preview: