Dredd fans are being urged to show their support for the film in a bid to help get a sequel made.
The campaign organisers have now declared that September 18 will be a Day Of Action for Dredd fans.
They said: "We're asking everyone who's signed the petition to come together next Wednesday and drive Dredd back up the charts.
"If everyone who's signed the petition bought an extra DVD or Blu-ray (either for themselves or as a present for a friend) or rented/bought it on iTunes and Netflix, it will send the loudest signal yet that WE WANT MORE DREDD!"
But if the mission doesn't pay off, Dredd's story is to continue in Judge Dredd Megazine.
Publisher Rebellion said Dredd: Underbelly "picks up where the critically acclaimed movie left off, with Judges Dredd and Anderson fighting the tsunami of crime on the mean streets of the dystopian Mega-City One".