flogging a dead horse

Verb

flog a dead horse (third-person singular simple present flogs a dead horse, present participle flogging a dead horse, simple past and past participle flogged a dead horse)

1. (UK, idiomatic) To attempt to get more out of something that cannot give more; to attempt to arouse fresh interest in something that is either hopeless or already settled.
2. (dated) To attempt to get extra work out of a ship's crew during the dead horse period.

   Synonyms:

   spit in the wind