Australian Langerak has started each of Dortmund's last two matches - a 1-0 Bundesliga win over Hoffenheim and a 1-1 draw with Anderlecht in the UEFA Champions League.
He has replaced long-standing number one Weidenfeller, who had started 12 of the first 13 league outings as well as Dortmund's opening five European fixtures.
Ahead of Saturday's trip to Hertha Berlin, Klopp has revealed that Langerak will continue for the forseeable future.
"Yesterday I had a very good conversation with Roman Weidenfeller," he said on Thursday. "Mitch will play in the next three games.
"In the new year, everything starts again. It is not a decision for eternity."
Klopp's side have endured a torrid start to their league campaign, winning just four of their first 14 matches to find themselves 14th in the table, two points off bottom.
"We are in a relegation battle, and we need to accept that," said Klopp. "We have accepted that."
Dortmund have been severely hit by injuries during 2014-15, and Lukasz Piszczek was forced to miss the draw against Anderlecht with a knock.
However, there was some positive news from Klopp, who felt sure the defender should be able to return, while Jakub Blaszczykowski made a late appearance on Tuesday, his first of the season following knee and muscle injuries.
"For Lukasz Piszczek there should be no problems," Klopp said. "And Sebastian Kehl completed light jogging yesterday.
"'Kuba [Blaszczykowski] is good, looks very fresh. I haven't decided for Saturday yet.
"I haven't made a decision whether Kuba and Piszczek will be on the pitch together on Saturday but it is possible."
