In the 2015 season, Reginiussen started the match in the opening game of the season against Aalesunds and helped them beat 5–0. However, during the match, he injured his Achilles and had to be substituted in the 65th minutes, resulting a successful operation but was sidelined for six months. In September 2015, Reginiussen returned from injury, playing for the reserve side to regain his fitness. It wasn’t until on 4 October 2015 against IK Start when he came on as a 78th minutes substitute, in a 4–0 win Reginuissen was given his first start since April 2015, captain the side to help them draw 3–3 draw against Strømsgodset on 25 October 2015. Reginiussen came on as a 72nd minutes substitute bench against Haugesund on 1 November 2015 and helped the side win 4–3, resulting the club becoming Champions for the first time since 2010 In the Norwegian Football Cup Final against Sarpsborg 08, he came on as a late substitute for Mikael Dorsin, in a 2–0 win to win the tournament. At the end of the 2015 season, Reginiussen went on to make five appearances for the side.