The students start with 3 Extra Lives for the Entire Year.

Those 3 lives are for redo's on Tests, Quizzes, Homeworks, Projects, or anything other than the final.  Extra Lives are for late turn ins or what ever the kid needs.  It's their "Get out of Jail Free" card.  No questions asked, 3 do-overs for the entire year.  

This has been one of the most useful aspects of Gamifying my classroom.