The rewards of righteousness are only available to those who are actually righteous. Repentance is the process by which you become righteous.
Repentance means making the changes necessary to bring your thoughts, desires, and actions into complete alignment with your sincere, present understanding of what God would do in your place.
If one had to reduce the definition of repentance to a single synonym, it would be improvement. Repentance requires: 1) perceiving potential improvement and 2) reconciling desires and actions to that improvement.
Potential improvement is typically already perceived in those seeking repentance. Awareness of a difference between the person’s ideal and actual behavior is what motivates the person towards repentance. For those who have already repented, they will perceive potential improvement when they encounter new information.