Batch Download Pictures From Website

Hi

Let's say I create a project with one task, and download the images.
But something goes wrong and I wish to perform this download again.
I found out that PL prevents me from doing this because he "remembers" what I have already downloaded, and won't download it anymore, even if I delete the pictures!

Is there a way to erase such "memory", so that I don't have to creare a whole new task?

Thanks ^_^

Main menu->Project->Database->Optimize project data.

Thanks!