There is no remedy for patent expiration. However, if the term of the patent right expires due to force majeure, the patentee may collect relevant evidence within 2 months from the date when the obstacle is removed, or at the latest within 2 years from the date when the term expires, and request the the State Council Patent Administration Department to restore the right.
Legal objectivity:
Article 44 of the Patent Law of People's Republic of China (PRC) is under any of the following circumstances: (1) Failing to pay the annual fee as required.