Aapki Kasam

Yes, you guessed it right.  It is about the song from "Aapki Kasam" (1974)

"Karvate Badalte Rahe.."

http://www.youtube.com/watch?v=xU1GfgurLr8&feature=relmfu

For Rajesh Khanna!

Following details from the same site as the song:
Music Director: R D Burman
Lyrics: Anand Bakshi
Singers: Kishore Kumar & Lata Mangeshkar