The Cobblers are eighth in League Two, with 13 games to play, after Tuesday's 2-0 win at Hereford United.
Manager Sampson told BBC Radio Northampton: "It'll take a lot of hard work. We need another nine wins, which is a tough ask.
"There's a lot of teams scrapping for those places. But others will lose points and I hope we can capitalise."
Nine wins would leave Northampton on 73 points in League Two.
Shrewsbury Town reached last season's play-offs with 69 points.
Just nine points separate fourth-placed Chesterfield with 13th-placed Morecambe.
Striker Adebayo Akinfenwa has been instrumental in the Cobblers' rise up the division, with three goals in their last four matches.
"We know if it's a quality ball into him, he's the best hold-up player in this league by a long shot," said Sampson.
Source: BBC Sport
Source: BBC Sport