The episode confirms a central rule of Lucifer : Lucifer loses his mojo when he hates himself and regains it when he acts out of genuine love and sacrifice—not because he feels worthy, but because his purpose is no longer selfish.
If you're interested in watching the specific episode where Lucifer gets his mojo back, I recommend starting from Season 6, Episode 5, "Nibbles." what episode does lucifer get his mojo back