Shah Rukh Khan, who played Raj Malhotra in the film, took to Twitter to announce the launch of the new trailer.
"My favourite line in a film ever... 'Nahin main nahi aaoonga...' DDLJ (ver 2.0 trailer reloaded)...I am so happy," he tweeted Tuesday.
A statement from the movie's production banner Yash Raj Films (YRF) read: "Starting Dec 12, 2014, YRF is looking at a slew of activities to commemorate the completion of 1,000 weeks of DDLJ's uninterrupted run at the box office."
"The film released Oct 20, 1995, and ever since has been playing out in the iconic Maratha Mandir, making it the longest running film in the history of Indian cinema."
It marked filmmaker Yash Chopra's son Aditya Chopra's directorial debut and featured SRK, Kajol, Amrish Puri, Farida Jalal and Anupam Kher in key roles.
As part of the celebrations, SRK and Kajol, who were last seen together in "My Name Is Khan", will appear on the television show "Comedy Nights With Kapil" to celebrate the occasion.
The film won 10 Filmfare Awards, including the awards for the best film, best actor, best actress, best director, at the 1996 edition of the ceremony.