The 34-year-old goalkeeper became No.1 between the sticks in January when Shay Given left the strugglers to join Manchester City.
But the veteran stopper has yet to taste victory at St James' Park and he is hoping Newcastle's bout of homesickness will not return to haunt them again when they play host to fellow relegation candidates Middlesbrough on Monday.
"You look back at the games earlier in the season that have cost us, like the equalisers against Wigan, Stoke and Manchester City - there's six points there," said Harper, whose side have only won four times at home all season.
"If we had beaten Hull at home, we would be out of the bottom three, but how far do you go back?
"We can't look back now - those games have gone. We have got three fixtures we can win, and we are going to try to win them all."
The situation at the foot of the table is so tight - Newcastle and Boro headed into the weekend three points adrift of safety with West Brom three worse off - that no-one yet knows how many points will be required to survive.
However, what is clear is that Alan Shearer's men will almost certainly have to beat the Teessiders and Fulham at home before they travel to Aston Villa on the final day of the season hoping their fate is in their own hands.
Massive gamesHarper said: "We have got to do the job. We have got the get the maximum points we can from the next three games, including two massive home games.
"This is a very tough league. We haven't performed for 90 minutes often enough.
"We have got to do that in the next three games because the Premier League is not a forgiving environment.
"We have got to do it for 90 minutes, or you are punished, as we have been by Manchester United, Arsenal and Chelsea."
The statistics do not make pleasant reading for Newcastle - they have won just one of their last 17 league games and have scored only four goals in their last 10 despite having strikers Michael Owen, Mark Viduka and Obafemi Martins back in harness for the last few weeks.
Shearer is yet to experience victory as a manager after five games at the helm, and he will hope for better things - and perhaps a stroke of much-needed luck - from a game he has admitted is the biggest of even his illustrious career.
Harper said: "A break or a decision would be nice.
"Mark Viduka had a great chance in the first half [against Liverpool], but he was given offside by the referee and the linesman hadn't given it.
"You would think he was going to score, and then the first goal [from Yossi Benayoun] was offside.
"We are due a break, a decision or a ricochet. We just need a bit of luck and hopefully, we will get some on Monday night."