I started a small project for me and a few friends to edit a few tables in a multi-database (mysql). Now the project is over several hundred pages and while it looks incredible on the ouside, it is stating to feel cluttered inside. no structure. here is what we have:

3 databases
several hundred tables make up the three DB.
The php project is designed to make it easy to edit these tables instead of manually.

does anyone have a suggestion how to organize the code. I a starting to see repeated includes at the top of files, certain code is starting to repeat (I have functions for the more common ones)
I would like to stay away from "CLASS" type programming (unless you feel this might be best) only because it is an open source project and some of my friends are not that great at php, so want to keep it simple. but for organization, I could go to class style. 

my biggest concerns is that the majority of pages (the html part) are tons of cut and paste. so each page is like the other. not sure how to consolidate those efficiently. I think once that part is figured out, the php code will trim up as well.

thanks