Mitch Brundle joined Dover on a two-year deal in June 2017.
The Londoner, who can play in midfield and at full-back, made 34 National League appearances for Gateshead, scoring twice, before making the move to Crabble.
Brundle joined the Heed from Braintree Town after making 77 appearances for the Essex club.
He was a member of Braintree side that finished third in the National League before losing to Grimsby in the play-off semi-finals in the 2015/16 season.
Brundle started his career in the youth ranks at Yeovil Town before joining Bristol City.
While at City, he made seven Football League appearances while out on loan at Cheltenham Town in the 2013/14 season.