Does a person's right to their usurped or stolen property cease if it is returned to them after years and they refuse to accept it, or will Allah exact retribution from them on the Day of Judgment, or will Allah bear their injustice on my behalf if He accepts my repentance?

It is not permissible for someone whose right has been restored to refuse to accept it, and the one who took it is not absolved until he returns the money to its owner. If the money is returned, the person is absolved, and the repentance is complete, by Allah's will, even if the owner does not accept it. It should be returned in the presence of witnesses so that it is not demanded again. If it is not accepted, it should be held as a trust until its owner agrees to take it, or it should be given to his heirs after his death.