The song, which released on Wednesday, shows an older version of Sidharth's Jai recalling moments spent with Katrina's Diya. It is a montage of their laughter, tears and separation.
A distraught Jai tries to catch hold of Diya in the present but fails.
Pakistani music-composer and singer Bilal Saeed has revised his 2013 chartbuster for the film.
Lyrics have been penned by Kumaar.
Produced by Karan Johar, Farhan Akhtar and Ritesh Sidhwani, Baar Baar Dekho will hit the screens on September 9. It also stars Sarika, Ram Kapoor, Taaha Shah Badusha, Sayani Gupta, Rohan Joshi and Rajit Kapur.
Watch the song here: