Hey. Hi~!

I created a beauty salon management program for a small project.
It has a few funtions but centainly necessary.
The 2nd semeter began already. I'm given a new project class
and I decided just to enhance my former program.

While I was making the program,
I comformed to the design procedure which is widely used in practice.
I drew up requirement specifications and drew actor-class diagram, use
case and related diagrams.
And then I extracted candidate classes and drew up data dictionary and
blah blah sequence, class diagrams also.

early procedure.
But now I wonder and am confused after look over the former
requirement specification.
I think to upgrade a program there will be a scheme or methodology
applied generally over software development field.

To sum up, is there a scheme or methodology to upgrade programs?
If It is, Could you let me know where I can learn it in the internet
or a book?