Add -newer only switch to your put command.
https://winscp.net/eng/docs/scriptcommand_put#neweronly

You can also use synchronize command instead:
https://winscp.net/eng/docs/scriptcommand_synchronize

Hello Everybody,

I want to upload files to my server, if they aren't uploaded before.
At the moment I use the attached script for uploading:

My problem is, that each file will be uploaded, even if the file exists. It'll overwritten and that mustn't happen!

I hope you can help
Friendly regards
Toby from Germany