There is a mitzvah to ask for forgiveness from somebody you’ve wronged on Erev Yom Kippur. Also the Mishnah in Yoma 8:9 states
With regard to one who says: I will sin and then I will repent, I will sin and I will repent, Heaven does not provide him the opportunity to repent, and he will remain a sinner all his days. With regard to one who says: I will sin and Yom Kippur will atone for my sins, Yom Kippur does not atone for his sins. Furthermore, for transgressions between a person and God, Yom Kippur atones; however, for transgressions between a person and another, Yom Kippur does not atone until he appeases the other person. Similarly, Rabbi Elazar ben Azarya taught that point from the verse: “From all your sins you shall be cleansed before the Lord” (Leviticus 16:30). For transgressions between a person and God, Yom Kippur atones; however, for transgressions between a person and another, Yom Kippur does not atone until he appeases the other person. In conclusion, Rabbi Akiva said: How fortunate are you, Israel; before Whom are you purified, and Who purifies you? It is your Father in Heaven, as it is stated: “And I will sprinkle purifying water upon you, and you shall be purified” (Ezekiel 36:25). And it says: “The ritual bath of Israel is God” (Jeremiah 17:13). Just as a ritual bath purifies the impure, so too, the Holy One, Blessed be He, purifies Israel.
What about repenting with the intention to time travel back before that repentance and transgress?
