payment for prior improvements.] Any such municipality, county or school district, shall at all times have a preference right to lease said state lands, and the commissioner of public lands shall prefer the application of said municipality, county or school district over any other application for lease upon the same land. Provided, nevertheless, that before any such lease is granted the lessee shall be required to pay the reasonable value of any improvements placed upon said state lands by a former lessee for the use of the owner of said improvements.