Regan has only played twice because of ankle and thigh injuries but he is now nearing full fitness and manager Paul Ince was eager to retain his services.
"We wanted to get Carl in for longer and get him back ready for another busy month," Ince told the club website.
"We are low defensively with Graeme Lee being out, along with Krystian Pearce.
"We only had Sam Sodje on the bench against Brighton, with
Stephen Hunt away at Lincoln.
"We've got players coming back and hopefully now we can start picking some points up."
Regan, who played under Ince at both Macclesfield and MK Dons, is out of contract with the Pirates at the end of this season.
Source: BBC Sport
Source: BBC Sport