If, upon the completion of the local improvement project, it is found that the assessment previously levied upon any parcel of real property is more than sufficient to pay the costs of such improvement, the council shall ascertain and declare the excess. When so declared, the excess shall be entered on the lien docket as a credit upon the appropriate assessment. In the event that any assessment has been paid, the owner of the parcel at the time the excess is declared by the council shall be entitled to the repayment of the excess.