to make up for one's mistakes or faults by doing good deeds or performing meritorious service

To reflect on one's actions in private and seek to make up for past mistakes; often used as part of the phrase [[进思尽忠，退思补过|進思盡忠，退思補過|jin4 si1 jin4 zhong1 tui4 si1 bu3 guo4]]

when in office, one thinks of serving with loyalty; when out of office, one thinks of correcting past mistakes