If an incognito window, or clearing all cache locally, doesn't update it, then it sounds like it's being cached on the server side. You probably want to check your server caching configuration (and CDN caching configuration if you use one). For example if your server is behind a CDN that does server-side caching of certain types of resources, like images, for 24 hours, then nothing you do on the client will be able to update that cache.
If all else fails, publishing your project to a different URL as you have been doing is the ultimate cache-busting approach.