Arnold's first season at the New Lawn was blighted by injury after former boss Ady Pennock snapped him up from Stevenage in the summer of 2014.
He finally made his debut in February 2015 and he went on the make fourteen appearance that season, including the play-off semi-finals against Bristol Rovers.
Despite another injury-marred start to his second campaign, the 6’5” stopper took over from Jonny Maxted in Rovers' 2-1 win over Wimbledon in the First Round of the FA Cup in November.
He played every minute of the remaining twenty-nine games, including the play-off semi-finals against Dover Athletic and Promotion Final against Grimsby Town at Wembley.
The 26-year-old made forty-five appearances in all competitions, including forty-three in the league, over a two-year spell at The New Lawn – he kept sixteen clean sheets.
Arnold played 45 minutes in Saturday's 2-0 win over Leyton Orient and battles it out with Mitch Walker for a starting spot.
Meanwhile, midfielder Mitchell Pinnock has signed a deal with the club to run until the end of the 2016/17 season.
He becomes the second summer addition to the Whites midfield, and has played 45 minutes in each of the club's pre-season friendlies thus far.