The Birmingham-born British forward arrived just before Christmas last season on an 18-month contract.
The 23-year-old played a major part in the double-winning Herd side in the second half of last season as he scored 21 goals in 35 games, having joined from Slough Jets, where he also netted 15 times.
Bison player/coach Doug Sheppard is really pleased to have one of his top goal scorers back for another season.
He said: “Ciaran did a great job for us last season and is someone I can play on any line. He has good speed and his lanky style makes him very difficult to defend against.”
Long is delighted to be suiting up for the Bison again and said: “There is great chemistry in this team and, with most of the guys back, this will give us a good start.
“We know it is going to be tough, but we will work hard as a unit and I see no reason why we cannot win a couple of trophies again.”