Search and Replace – multipage, long string of code

I am looking for an easy and simple search and replace tool/plugin/app that I can use on our Striker WP theme. We have a link for our app download pasted individually on each page (Over 200 pages). we have tried many “search and replace” apps out there but none can handle a longer string of text/code. I really don’t want to have to go to each page to replace text.

Any help would be great!