Mentioning that you've contacted an agent before

I was just wondering what people's thoughts were.

I've submitted to a particular agent within the past year--it was probably seven or eight months ago. She passed on the project (though she did ask for a partial).

Now I have a new MS and project. When querying this agent (she's a very good prospect for my genre, historical), should I mention that I've contacted her before about a different project? Or should I just submit the new one without mentioning the old one that she passed on?

Alright. I thought I probably shouldn't. I just didn't want to come off as disingenuous if she remembered the last project. Though I know full well how unlikely THAT is, having worked at a literary agency. The number of submissions is overwhelming!