While I'm certainly no droplet expert, I'm afraid what you want can't be done, directly.
What you could do is have the droplet save to a specific location though. If you make this specific location an alias to where you really want your images to end up, I think this would work. The only problem would be that you'd have to change the alias every time you process files from a different location.
Another option would be to simply move them after you've processed them.
Hope this helps,
Hayo