Nethers, who was club captain under Mark McGhee and voted Player of the Year five years ago, has enjoyed a successful three-month loan spell with Tony Adams' Wycombe side and has been an ever-present in The Chairboys defence since arriving at the club.
"Everything is finalised here now and I'll be here until the end of the season," Nethercott told the club's official website.
"I'm very pleased to be here and I'm sold on the club. I love the place, I love the surroundings and I love the lads."