The centre-half played a key role in the heart of defence this season but frustratingly his campaign was cut short due to injury.
Harrison joined the club in the summer after leaving Gloucester City and quickly became one of the first names on the team sheet with the Hoops.
He also scored vital goals in back-to-back games against Dulwich Hamlet & Cheshunt as City started their play-off push.
Speaking after signing his new deal with the club, Harrison said: “The lads and staff were absolutely brilliant last year, both on and off the pitch.
"Although I was injured after the thirty odd games, I still felt part of the team in the successful campaign.
"I'm looking forward to continuing our journey in the National League."