This type of caching behavior happens mostly on the server side, especially if you're using static files. Also CDNs tend to cache them if you use static files. This is not Jasonette's fault because in many of these cases you would see the same JSON being cached if you open on a web browser.
If you're using static files, try busting your cache by appending the url with parameters (for example
Or if you want to keep it simple during development, try using jasonbase I built it exactly because of this inconvenience and use it for all my development because it never caches anything.