I don't believe repentance is a work. Repentance is about asking God to forgive you and cleanse you of your sin. It is all about throwing yourself before God and His mercy. It is not something you can take credit for. You can't take credit for repentance because God is the one who is cleansing you of sin when you seek His forgiveness. You are trusting in God to forgive you (And not yourself to be forgiven). It's about throwing yourself down before Him. For if we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. We trust and believe in 1 John 1:9 by faith. Our faith in God's promise to deliver us from unrighteousness when we admit our faults before Him is what it is all about. For who was more justified in the Parable of the Tax Collector and the Pharisee? (Luke 18:9-14). Titus 3:5 says we are saved by His mercy and by the washing of the regeneration of the Holy Ghost. In other words, John the Baptist said bring forth fruits worthy of repentance. Fruits are works; And repentance is not labeled as a fruit (or work).
Then said they unto him,
"What shall we do, that we might work the works of God?"
Jesus answered and said unto them,
"This is the work of God, that ye believe on him whom he hath sent." (John 6:28-29).
In other words, one needs to be born again spiritually by repenting of their sins and accepting Jesus (i.e. believing on Jesus). Then God can do the good works thru them (1 Corinthians 15:10) (Philippians 2:13). The works they do are in yielding to the fruits to the Spirit after they accepted the Lord. They are saved by God's grace and mercy. For if a person messes up, they have his grace to fall back upon. God will work with a person and give them time to do the "good work" within their life. It is not usually an overnight process of a Christian being turned into a super Christian instantaneously. For even the great men of faith were not perfect at the start of their life. Their faith was a walk with God and a trust in Him (Whereby holiness and fruitful works eventually flowed as a result from their faith or belief in God). But Abraham was saved before he did any works for God. The thief on the cross was saved without works. Yes, a believer cannot live an immoral life style or flat out reject the commands in the Bible for their life. But a believer (that is elected or chosen) will not live in such a way habitually (Like the world) because they surrendered to God whereby He lives within them and whereby He will convict them to do what is good and right (By the power of His Spirit).