You can download your game from the online editor and continue edit it from the windows program. Is there a way to upload a game from the windows program and continue edit it in the online editor?

No.

Is there a way to upload a game from the windows program and continue edit it in the online editor?

Depends.
Web editor? No.
Editor for this website? Yes/Maybe.
I think Alex once had the capabilities for it, but now only a few may possess the ability to do it.