The Pilgrims finished seven points adrift of the play-off places last time out after threatening to gate-crash the top seven.
But there's no time to lick their wounds, Elliott explained to Lincolnshire Live.
“It’s going to get stronger again, you’ve got to be honest about that," he said.
“It’s going to be another difficult league. I really think it’s one of the hardest leagues in non-league.
“There are 12 or 13 teams definitely in with a chance of promotion."
Elsewhere, Boston added Simon Ainge to their ranks from National League North rivals Darlington.
“[Ainge] has vast experience in this league and is very much the aerial and physical presence in both boxes that we lacked last season," the Pilgrims' boss told the club's website.
“He has shown a lot of determination and hunger to make this deal happen and I am very much looking forward to working with him.”