Striker Jamie Allen joined Dover in May 2017.
Allen arrived from Southport for an undisclosed figure on a two-year deal.
The forward was Southport’s leading scorer in the National League last season with 10 goals in 35 appearances.
He was also on target for Port in their 2-1 win against Dover at Crabble in March last year.
Allen joined Southport in the summer of 2015 from Fleetwood Town, where he had made five senior appearances, including scoring on his Football League debut at Northampton Town.
That strike was later voted as the club’s goal of the season in 2012/13.
While at Fleetwood, Allen also had loan spells with AFC Fylde and Stalybridge Celtic.