This has been covered numerous times and is found easily via search. This will only work as long as you haven't made use of any new features after r195.
Summary:
1. Go to the project file. If it's a .caporj file, skip step 2.
2. If it's a capx, unzip it (capx are just zip files basically).
3. Now, open the caproj file in a plain text editor.
4. Look for the following string, minus quotes: "<saved-with-version>". It's only a few lines down from the top.
5. You'll see this tag has a 5 digit number; it's the c2 version padded with 2 zeros (so, r200 will look like 20000). Change the first 3 digits to match version you want to revert to, i.e. 19500.