Dortmund finished runners-up to Bayern Munich in the Bundesliga and also came up short to their German rivals in the Champions League final.
Klopp has urged his side to cut out "unnecessary" lost points, pointing at Bayern's 25-point lead last season.
"We want to learn from the mistakes we made last year," he told reporters. "This is our most important aim.
"We conceded far too many goals, we were 25 points down to Bayern - even though we didn't lose against them in the league.
"So we lost 25 points against all the other teams and I remember countless lost points that were absolutely unnecessary."