In the event that the taxpayer shall receive, by whatever means, a reduced assessment with regard to part or all of his, her or its property which is currently the subject of the tax exemption provided in this Part, such reduced assessment shall be applied proportionately to the portion of the assessed value which is subject to a tax exemption and the portion of the assessed value which is not subject to a tax exemption, and shall result in a reduction of tax exemption which was initially granted for purposes of the number of exemption years still remaining on the exemption schedule.