Repentance is a lot more than just changing one's mind.
As Paul rightly noted:
II Corinthians chapter 7
[8] For though I made you sorry with a letter, I do not repent, though I did repent: for I perceive that the same epistle hath made you sorry, though it were but for a season.
[9] Now I rejoice, not that ye were made sorry, but that ye sorrowed to repentance: for ye were made sorry after a godly manner, that ye might receive damage by us in nothing.
[10] For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death.
[11] For behold this selfsame thing, that ye sorrowed after a godly sort, what carefulness it wrought in you, yea, what clearing of yourselves, yea, what indignation, yea, what fear, yea, what vehement desire, yea, what zeal, yea, what revenge! In all things ye have approved yourselves to be clear in this matter.
True Biblical repentance results in "carefulness" (not to commit the same sin again), a "clearing of ourselves" (by no longer being guilty of the sin), "indignation" (against the sin we had been committing), "fear" (not to commit the same sin again and possibly face judgment), "vehement desire" or "zeal" (to do what's right), and "revenge" (against our previous disobedience).
That's a lot more than just changing one's mind.
Biblically speaking, we must not only repent, but also bring forth fruits worthy of repentance:
Acts chapter 26
[12] Whereupon as I went to Damascus with authority and commission from the chief priests,
[13] At midday, O king, I saw in the way a light from heaven, above the brightness of the sun, shining round about me and them which journeyed with me.
[14] And when we were all fallen to the earth, I heard a voice speaking unto me, and saying in the Hebrew tongue, Saul, Saul, why persecutest thou me? it is hard for thee to kick against the pricks.
[15] And I said, Who art thou, Lord? And he said, I am Jesus whom thou persecutest.
[16] But rise, and stand upon thy feet: for I have appeared unto thee for this purpose, to make thee a minister and a witness both of these things which thou hast seen, and of those things in the which I will appear unto thee;
[17] Delivering thee from the people, and from the Gentiles, unto whom now I send thee,
[18] To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me.
[19] Whereupon, O king Agrippa, I was not disobedient unto the heavenly vision:
[20] But shewed first unto them of Damascus, and at Jerusalem, and throughout all the coasts of Judaea, and then to the Gentiles, that they should repent and turn to God, and do works meet for repentance.