The board shall cause notice to be served upon the owner of any tract of land or easement against which it is proposed to increase the assessment, requiring the owner to appear at a fixed date and show cause why such assessment should not be so increased. Such notice shall be served for the time and in the manner prescribed in section 468.15 or section 468.16, as the case may be, except that personal service in the same manner as an original notice may be made in lieu of the other methods.