Did you have your notes sync with your Samsung account? If so, it's all safe in the Cloud, it's the process that's not as intuitive. You have to go to S-Note, go to "All Notes", hit the menu button and select IMPORT. Same thing should apply, I guess, if you have the files in your phone/SD Card. Note, however, that the format will change and whatever changes you make in the new version will not be editable in older versions of S-Note.