Question about re-querying an agent

Hi. I just had a question in regards to querying an agent I had queried before, but now with a somewhat new project. The project I had originally queried was part of a series, but could act as a stand alone. A few of the agents who sent a personal rejection to me made some specific comments and I took a chance and asked them if I could query them with the next book in the series (again, a stand alone), feeling that I had taken care of the things they had specifically commented on. My question is: when I query these agents again with this new project, do I also include the original emails we had exchanged, or do I just put in a sentence in my letter stating our previous communication?
Thanks for your help.

Thank you both for the advice. But--now I need a third person to break the tie

I guess I'll do both things--do a brief sentence and hit "reply." At least this way I can remind the agent of my previous project and she can see the improvements I have made based on her comments.
Thanks again.

Thank you! I'll be hitting that reply button when I write to her. Thanks again.