Repentance is not a one-time act to get us into heaven, but an entire way of life to maintain Christian joy. Repentance isn't a work tack onto our faith that restores our fellowship with God. Repentance is faith. Tim Chester helpfully illustrates how faith and repentance and faith are one. He writes:
How do we repent? We repent through faith...turning to God in faith and from sin in repentance are the same movement. Try it now. Stand facing the window. Then turn to face the opposite wall. The act of turning from the window and turning towards the wall is one movement. You can't turn towards the wall without turning away from the window. And you can't turn to God in faith without turning away from sin in repentance.
True repentance includes faith. Repentance and faith are two sides of the same gospel coin, one movement made possible by grace. This gospel grace is at our disposal continually in Christ. Martin Luther said: "The entire life of believers is to be one of repentance." Why our entire lives? Because in our everyday failures, we have every opportunity to turn to Jesus for grace and forgiveness.
Jonathan Dodson, Gospel-Centered Discipleship