Best way to deal with server side includes in 10-year old website

I have a client's site with over 800 articles, originally done in .asp using server-side includes. Recently I updated Dreamweaver to 2018 cc which no longer shows these includes. I've spent several days trying to figure out the best way to deal with this problem. A good portion of each page is built using these, in particular a very long list of stories that uses an extension that creates a tree menu that opens and closes - way too much code to have on every page.

I've figured out a way of doing it with jquery, but I still can't see anything unless I'm in live view, and I have to keep uploading the css over and over to see it. I'm finding it difficult and very slow to work this way.

Would it be better for me to go back to an earlier version of Dreamweaver that allows me to see them (this seems like problems for some future day), or convert the whole site to php so I can use that type of include? Or some other method?

Also, I'm not a coder, I'm a designer, so it can't be too complex.

Thanks for any advice!