With eight games remaining, the Premier League's bottom club are seven points from safety after they "threw away" victory at their relegation rivals, according to Redknapp.
"It's a setback but we can't go feeling sorry for ourselves," he told QPR's website. "We've got to keep going.
"There are still games to go. If we keep playing well we can win four of five games."
QPR, who sacked Mark Hughes earlier this season and have spent liberally trying to preserve their top-flight status, have 23 points, the same as second-from-bottom Reading.
Redknapp has said 37 points should be enough to stay up, but that would mean collecting 14 points of the 24 available - a tall order considering how their season has gone.
They were on course for three of them on Saturday after Jermaine Jenas gave them the lead in a first half they dominated.
But Gabriel Agbonlahor turned the match with an equaliser in first-half stoppage time.
Andreas Weimann put Villa in front, and although Andros Townsend made it 2-2, QPR were undone as Christian Benteke scored an 81st-minute winner for Villa to take them six points above the relegation zone.
Redknapp was scratching his head at how his team had come away with nothing.
"I'm upset for the lads, I thought they played well today," he said.
"We've not lost through a lack of effort. We were fantastic in the first half. It was so one-sided it was unbelievable.
"I wanted to come in (at halftime) 1-0 up, even though it could have been more. Instead they've suddenly got a lift after being awful.
"They couldn't believe their luck. We threw it away from where we were."
Villa, who looked in severe danger of relegation, have beaten Reading and QPR in consecutive weeks and there appears to be light at the end of the tunnel for boss Paul Lambert, whose squad is one of the youngest in the Premier League.
"We've been playing well for a number of weeks now," Lambert told the BBC. "There's a long way to go. This is the first time this football club has won back-to-back games since 2011.
"It's an incredible stat. But the noise of the stadium, the crowd with us, we are certainly playing well enough."