Upon his own initiative, or upon the application of any party in interest (including an employer or carrier which has been granted relief under section 908(f) of this title), on the ground of a change in conditions or because of a mistake in a determination of fact by the deputy commissioner, the deputy commissioner may, at any time prior to one year after the date of the last payment of compensation, whether or not a compensation order has been issued, or at any time prior to one year after the rejection of a claim, review a compensation case (including a case under which payments are made pursuant to section 944(i) of this title) in accordance with the procedure prescribed in respect of claims in section 919 of this title, and in accordance with such section issue a new compensation order which may terminate, continue, reinstate, increase, or decrease such compensation, or award compensation. Such new order shall not affect any compensation previously paid, except that an award increasing the compensation rate may be made effective from the date of the injury, and if any part of the compensation due or to become due is unpaid, an award decreasing the compensation rate may be made effective from the date of the injury, and any payment made prior thereto in excess of such decreased rate shall be deducted from any unpaid compensation, in such manner and by such method as may be determined by the deputy commissioner with the approval of the Secretary. This section does not authorize the modification of settlements.