Students who are required to repeat a subject at university are often not only low achieving, but also unmotivated and lacking in self-confidence. In this study, we evaluate the effect of implementing a combination of three innovative techniques (flipped classroom, team-based learning and frequent testing) in groups of students who are repeating a subject. We assess the impact of the new teaching strategy on the final course grade through econometric analysis. Our sample consists of more than a thousand students who were repeating a subject in the Bachelor's degrees in Business Administration or Economics of the University of Barcelona. ...