Neb. Rev. Stat. § 14-540

In cases of omission, mistake, defect, or any irregularity in the preliminary proceedings on any special assessment within a city of the metropolitan class, the city council shall have power to correct such mistake, omission, defect, or irregularity, and levy or relevy a special assessment on any or all property within an improvement district, in accordance with the special benefits to the property on account of such improvement as found by the city council sitting as a board of equalization. The city council shall deduct from the benefits and allow as a credit, before such relevy, an amount equal to the sum of the installments paid on the original levy.