When the assessments as provided for in sections 31-201 to 31-222 shall be inadequate to complete the work proposed, or when assessments shall be necessary for the maintenance and repair of such ditches or drains, each tract of land shall be assessed by the county board such proportion of the additional costs as its original assessment bore to the total original assessment, and the said additional assessment shall be made and collected in the same manner as nearly as may be as the original assessment was made. In all subsequent matters in relation thereto, the same proceedings shall be had as hereinbefore required in regard to the original assessment.