Is it possible to change the source file of a clip?

Hey guys, im new to the forum and a noob editing videos. The thing is, im editing a movie for a friend, making it shorter by removing some irrelevant scenes and stuff like that. I got the movie from a USB he had, and he told me to add subtitles, so i hardsubbed the movie and proceeded to edit the movie. After everything was done, he told me that the subtitles are too small, that he needs them bigger, but the problem is that if i can’t change the subtitles for the current file i worked with, so i have to hardsub the one he handed me again, and work with that new subbed movie, but i don’t want to re-edit it again because i did lots of cuts and added some transition effects, so i was wondering since im going to use the same movie, with the same length, can i just replace the source file or something like that so i don’t have to re-edit it?

Thanks in advance!

via Video Editing Forums: Digital Director – Adobe Premiere, Premiere Elements, and After Effects