Whenever the Council deems any special assessment invalid or defective, or whenever a court adjudges an assessment to be illegal in whole or in part, the Council may cause a new assessment to be levied for the same purpose, whether or not the improvement or any part thereof has been completed, or any part of the special assessment collected. In reassessment proceedings hereunder, it shall not be necessary for the Council to redetermine the necessity of the improvement or to hold a hearing thereon. If any portion of the original special assessment is collected and not refunded, it shall be applied upon the reassessment, and the reassessment shall, to the extent, be deemed satisfied. If more than the amount reassessed is collected, the balance shall be refunded to the person making such payment.