As it is known that its hard to edit the minified files and thus we prefer to edit minified files. Is there a way that the changes we make in unminified files are reflected in unminified files? Or is there a better technique to deal with this problem in bootstrap?
If you are looking to edit the core bootstrap files which is what it sounds like, that's not a very good idea as it could have unforeseen impacts on the rest of your site.
It is far better to simply overwrite the bootstrap style that you want to change in your own css.
If you are talking about your own minified files, I would recommend getting a plugin for you text editor. I use brackets editor with this plug in https://github.com/abagshaw/brackets-minifier and whenever you save a CSS file you can do ctrl+alt+M to minify and overwrite your minified file. But all decent editors will have similar plugins available.
Hope this helps :)