The Poland international says he wants to lift the DFB-Pokal with the club before he departs to join arch-rivals Bayern Munich in the summer.
Jurgen Klopp's side beat Wolfsburg 2-0 on Tuesday night to secure its place in the DFB-Pokal final, where it will face the winner of Wednesday's clash between Bayern Munich and Kaiserslautern.
The Polish striker says he wants to win the cup with his team before he leaves to join rivals Bayern in the summer.
"I want to win another title here - that's very important for me," the Poland international told the Bundesliga's official website. "I'm going to fight to the very last minute for Dortmund."
The 25-year-old scored his 100th goal for BVB to secure the win over Dieter Hecking's side and unveiled a t-shirt with his new tally on it during his celebration and he says it won't be his for the club.
"That was my idea," he said of the t-shirt. "I just had a good feeling that I would score a goal. Obviously I'm delighted with my 100th goal for BVB, and it was a nice goal too, but there’ll be more to come. We've still got four more games in the Bundesliga and the final in Berlin."
Dortmund defender Mats Hummels reiterated Lewandowski's desire to win the cup this season and insists the campaign has been a success, despite the side's elimination from the Champions League and failure to challenge Bayern to lifting the league title.
"Of course our aim is to lift something this year," the German defender said. "We're now just one win away from lifting the cup and that's exactly what we had hoped for. Given all our worries and injury problems, we've played a fantastic season."