Shadow Copy: Force Copy Creation?

Is there a way to force Vista to save a previous version of a file
while you're making and saving changes to a file?

I was modifying an image file. Saved it. And then I proceeded to make
more changes and save those changes. I then realized that I wish I had
the previous version of my file before I made the last change. I went
to restore the previous version using Shadow Copy but the last
restoration point was a few weeks ago, the last time I made changes to
the file before today. There were no restoration points from today.

So my question: is there a way to tell Vista to make new restoration
points while you're saving a file, instead of making them at
predefined scheduled times?