Sounds like a server issue to me. But I could be wrong.
Does the same thing happen if you upload with a separate FTP client (like FileZilla)? If so, then the problem is solely on the server side, and you’ve asked your question in the wrong place
I am assuming by “using the FTP function”, you mean you are using the NppFTP client to remotely edit files on your server. If you mean something different, please clarify. If that is what you mean, what version of NppFTP are you using?
How do you determine “it upload with success”? Does the NppFTP - Output window (which can be enabled by the show messages window button in the main NppFTP interface) show “Upload of /path/to/filename succeeded.”? If so, do you really need to “click upload many times”, or is that multiple clicking just an attempt on your part trying to make the file accessible through your browser? Or do you have some other confirmation (other than not getting the updated file in the browser) that the file has not made it to your server, even though NppFTP claimed the upload was successful? If so, what is your other confirmation? (One possible confirmation: attach to your server using an external client, such as Filezilla or PuTTY-ssh, and confirm that the file has changed)
Assuming the file made it correctly to the server on your first click of the upload (and being patient enough for the transfer to complete), then the problem is solely on the server side, and you’ve asked your question in the wrong place.
server-side freebie advice: My guess is that if it’s correctly uploading, then there is a problem in communicating between the server and the browser that the file has changed. That might be as simple as timezone difference or misconfiguration: when you upload a file to the server, most webservers I’ve seen will send that stamp to the browser (when request) so that the browser can decide whether or not to download the new copy. Sometimes a bad timezone setup on the server, or sometimes web ISPs use a different machine for FTP connections than they do for the external web connections, so a date mismatch there will cause the file to appear to have been modified at an earlier time, so the browser doesn’t recognize it. (I seem to remember from years ago that some FTP clients allow you to specify a timezone offset for a given server, but NppFTP 0.27.4 does not appear to be one of them, and I cannot see those settings in my modern Filezilla 3.34.0) Also, even with the times correct, a webserver may have its own caching mechanism, and might not poll your particular file for some number of seconds or minutes before it notices the file has changed and starts serving the new Last Modified Time to the browser.
We’re happy to answer Notepad++ questions, and NppFTP is reasonably connected enough that we’ll do our best (though we may have to pass you on to NppFTP experts at some point).
But unless you share some evidence that it’s unique to the Notepad++ setup, then you’ve asked your question in the wrong place, and should probably find a better forum for experts in the field you’re using (ie, for your webserver).