Whenever a less period of time than the maximum prescribed in section 42-204 has been granted by the department of water resources for making proof of beneficial use, upon a satisfactory showing being made by the permit holder, the department can extend the time for making such proof of beneficial use, but in no case shall such extension or extensions, including the original time granted, exceed the maximum prescribed in section 42-204. The department shall grant no extension unless the application therefor be filed with it prior to the date upon which the proof of beneficial use was required to be made under the original terms of the permit.