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.
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.