Use the noun tabula rasa to describe the chance to start fresh, like when a student's family moves and she gets to begin the year at a brand new school with a completely blank slate.
An opportunity to begin again with no record, history, or preconceived ideas is one kind of tabula rasa. Architects use the term to describe the place where a torn-down building once stood, which they now see as an opportunity to start over with a new, better, structure. The Latin literally means "scraped tablet," sort of an old-fashioned Etch A Sketch ready to be drawn on.