The easiest thing would be to download the latest OTR package on the website and treat it as a separate portable install to your current installation. I think Reaper 7.07 is included in it, but you can update to the latest reaper by downloading it from reaper.fm and pointing it to your otr directory during the install process. I believe there is a checkbox for portable install that needs checked as well. All of your projects should open fine in either version. In fact, any OTR project will open in any installation of Reaper, but you will lose some functionality of the workflows OTR provides.