the bible talks a couple of times about God changing his mind about a person, one of them is about king Saul and how he disobeyed God, 1 Samuel28:16 Then said Samuel, Wherefore then dost thou ask of me, seeing the Lord is departed from thee, and is become thine enemy? so I see this song as a prayer of repentance and seeking to please God again, a pure and sincere prayer, an honest repentance, is a door for the Holy Spirit to work in us.