One of the core beliefs of Christianity is that God the Father, God the Son and God the Holy Spirit are immutable persons.  They do not change.  Scripture says: For I, the Lord, do not change (Mal 3:6) and “ the Glory of Israel will not lie or change His mind; for He is not a man that He should change His mind” (1 Sam 15:29).  Yet we read:
And the Lord God was sorry that He had made man on the earth, and He was grieved in His heart. And the Lord said: I will blot out man whom I have created from the face of the land, from man to animals to creeping things and to birds of the sky; for I am sorry that I have made them. (Gen 6:6-7).
So the Lord changed His mind about the harm which He said He would do to His people (Ex 32:14).
I regret that I have made Saul king, for he has turned back from following Me, and has not carried out My commands (1 Sam 15:11).
Perhaps they will listen and everyone will turn from his evil way that I may repent of the calamity which I am planning to do to them because of the evil of their deeds (Jer 26:3).
Now therefore amend your ways and your deeds, and obey the voice of the Lord your God; and the Lord will change His mind about the misfortune which He has pronounced against you (Jer 26:13).
The attribute of immutability does not mean God has a frozen, machine-like response to events.  The Father, the Son and the Holy Spirit are living persons with uncountable emotions that surface in response to the affairs of creation.  The three persons who are one God do not change their character, person or plan, but a variety of emotions rise to the surface as events transpire before them.  (Kaiser et al., p 108 and 209)