Musar sobre Sanedrín 10:7

If a man has repented and then returned to his former wrongdoing, even if he has repeated this many times, he can nevertheless still repent. But it is necessary to make repentance more severe the second and third time than it was the first time. We have learned in the Jerusalem Talmud: he who has been wicked all his days and has repented, the Holy One, Blessed be He, receives him. Rabbi Johanan said, "Not only this, but all his transgressions, now that he has overcome them, are considered as merit" (T.P. Peah 1:1). And in the chapter (of the Babylonian Talmud) entitled, "Yom Kippur Atones" we read (Yoma 86b) that if he repented out of love of God, the intentional sins that he committed become merit; if he repented out of fear of God, then his intentional sins become as sins committed unknowingly. And as for all those that have no portion in the world to come and are condemned to Gehenna for generations — they are the ones who died in their wickedness. But if they repented, nothing can stand in the face of repentance. And a man should not think, "Since I sinned and caused others to sin I cannot repent," for he thereby weakens his hand from doing repentance. God forbid that he should do this, for the Sages said in the chapter entitled, "A share in the World to Come" (Sanh. 102a), even Jeroboam who sinnned and caused others to sin — even to him the Holy One, Blessed be He, said, "Now you must repent." And he did not want to (Pirke de-Rabbi Eliezer, chap. 43; Menorat Hamaor, item 254; and see T.P. Sanh. 10:2).