Retrieval practice for me goes hand-in-hand with spacing or spaced practice. In the 2018-2019 academic year I tried various retrieval ideas, but settled on setting spaced/retrieval homework, and completing starter low quiz tests twice a week (I teach most classes 4 times a week, for 50 minutes). 

Thanks to @BeckyHall75 on Twitter who gave me the idea of making up these quizzes: last lesson; last week; last unit; last year. Making these quizzes can take a little time, but they are invaluable to students.