The Cobblers lost Jason Crowe, Mark Hughes and Giles Coke at the start of the season, despite contract offers.
But, this time, Sampson told BBC Radio Northampton: "I expect 100% of those offered to sign. It's black and white for me, take it or leave it.
"We've spoken to five players and we'll speak to more next week. No-one's said yes, no-one's said no."
Sampson added: "There's some who might want to think about it, to see what's out there.
"That becomes a problem, because it's not always better anywhere else.
"When I signed a new contract, I was always happy.
"If you're enjoying the football and the training, you don't need to go to another club for £50 or £100 extra."
Ian Sampson took charge of the Cobblers in September, after Stuart Gray was sacked.
The team now lie 10th in League Two, five points off the play-offs.
"It's a busy period for me and a test as a manager," added Sampson.
"In terms of developing players, it's important to nail them down for the future. And obviously you want to keep your best players, but budget comes into it."
Sampson says he never had an agent as a player, but has no problem dealing with them in his managerial capacity.
"I don't see the point of having an agent at this level.
"But, if the player is happy to have an agent represent them, that's fine with me."
Source: BBC Sport
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