Collier and assistant Gary Horgan will remain until at least 2020 with the Bluebirds taking to their new surroundings well following promotion last year from the Southern League.
Town are 14th and their manager have belief that a top half finish is achievable.
Chairman Neil Blackmore says he had no hesitation in keeping the duo at the club and thanked them for all they have done.
“I am pleased to announce that both Mark Collier and Gary Horgan have agreed terms to continue as first team manager and head coach for at least the next two years," Blackmore said on the club's website.
“Both Mark and Gary have worked tirelessly this season to ensure we kept our place in the Nation League South and I felt it only right that their commitment and effort be rewarded with contracts and to show the board’s commitment to them.
“We are looking forward to working with Mark and Gary for many seasons to come and as this season comes to a close we continue to work hard with both on-field and off-field projects to move the whole club forward towards the next step.
“I would like to take this opportunity to thank Mark, Gary and all their back room staff for the hard work they have put into this season.”