to start to work or play more effectively or quickly than before.
With just five lengths to go, the German swimmer stepped up a gear and edged ahead to win the race.
move up a gear
To begin to do something in a more energetic, vigorous, or effective manner than previously. They're going to have to move up a gear if they want to beat the returning champions.I notice that you've really moved up a gear with your work lately. Great job!