I haven't dated in 25 years, so take this with a very small grain of salt:
I learned -- but only retrospectively -- that the women who were 'right' for me were the one's I was truly comfortable with early on. I can remember, when I found someone really attractive, fooling myself into thinking I was comfortable even in the times when I knew that I really wasn't. But, I learned that it wasn't about her level of attractiveness that mattered (although I ruled out many women based on looks), but the degree of ease at which I felt in her presence. Fact is, if you are comfortable, the likelihood is that she is also (and if she isn't, she'll just say no). Be honest with yourself -- if you really think you were at ease with this woman, then approach it that way -- call her believing that you'll continue the calm, easy rapport you already began.
Doesn't matter that she is great looking -- if you are a basket case around her, it probably won't work. If you were as comfortable and natural as you seemed to convey in your post, then I think you have a great shot at a second date. If it's a 'go', do something that you think is fun -- you are more likely to show a calm, positive side, and you'll see whether the things you think are fun are things she thinks are fun. Best of luck!