The Reading-born attacker, who can play in the centre or on the wing, is the ninth player to commit to the Devils next season.
And Kelman enthused about his role in the team so far, since signing from NAHL side Jamestown Rebels in October 2018.
“When we originally signed Sam back in 2018, we knew we were getting a great young player that had tons of potential,” Kelman said. “He has progressed even quicker than we anticipated.
“Sam is only 22 years old and is getting better and better each season and I expect a big season out of him this year.
“He is a workhorse, loves the game and I think he has really benefited from being around the older guys on this team.
“I love the way he plays, all energy every shift. He can adjust and play on any line and he showed that last season. He has great speed and as he gets stronger, he is going to develop into a great power forward in this league.
“As a guy, we just love him. He is great with the fans and makes time for everyone. His teammates absolutely love him as well. He just fit in right away when he arrived here and hopefully he will be here for years to come.”
Duggan is the third name to be added in the last week following Josh Batch last Friday and Toms Rutkis, who was announced on Wednesday.