The loss has left Redknapp's side seven points adrift of safety, but the 66-year-old insists that it is not impossible and remains confident of an escape.
"We need to win four or five games. It is not impossible. While there is hope, you keep believing," Redknapp told BBC Sport.
"It is hard with the points situation, but we cannot be playing any better. We are playing very well, that is all we can do.
"With eight games to go, we need to keep trying to win the games. If we can do that, we can still do it."
Redknapp was appointed manager at Loftus Road in November, taking over from Mark Hughes.