by accident deleted an image from "Last Import" - how to get it back to that folder?

When I edit an image, for instance with the repair tool, it sometimes happens to me that I push the del-key. Then the image disappear. Sometimes I find it in the trash, sometimes only in the Folder from that particular date. Very anoying!

Undo doesn't work. 

I cant find any command, to get it back to the Last-Import-Folder, where the other images are still visible. I also can't move it via drag and drop to that folder.

What am I missing? Latest update installed