The Loftus Road side is currently seven points adrift of safety at the foot of the table, with the first game up a home fixture to league leaders Manchester United, but Redknapp still believes it is possible to avoid relegation.
"We need to close the gap," Redknapp told reporters."We need 20 points at least. Whether that would be enough I don't know but we have to try for that."
He added, "Of course I feel we can do it. If I stop believing everyone does. I still think it is possible with 12 games to go and lots of points to play for, six points can turn everything around so quickly."
QPR has struggled with injuries this season, particularly up front. January signing Loic Remy has been out since suffering a groin injury in training earlier in the month and the former Marseille forward could make his return on Saturday, while Redknapp reiterated Bobby Zamora will likely require surgery in the summer.
"We have a pretty fit squad. Remy has trained the last couple of days and looks OK," Redknapp stated. "We will have to see how he is and whether he can play. He trained yesterday. It is difficult with groins. We don't want to risk him.
He added, "Bobby might need an operation at the end of the year but the aim is to keep him going for the next 12 games.
"We are hoping we can get more than half a game from him but we will see how we go."
On Saturday's opponents, Redknapp admits he would be "very surprised" if Manchester United didn't go on to win the Premier League this season with the quality they boast in their squad.
"I'd be very surprised if they don't win the league from where they are," Redknapp said. "They have kept winning and other teams have had bad runs. They have been the only team playing with consistency so it has left them in a great position.
He added, "[Wayne] Rooney is a top player. But they are full of top players that is why they are so far clear."