How can I hint to my ex-girlfriend that I still have feelings for her?

Long story short, I recently decided that I want to try to get back together with my ex. We regularly talk over the phone (since she goes to school in NC and I'm in VA), and I was wondering what's a good way to subtly show my feelings for her? I don't want to be too direct, since I'm really not sure how she feels about me, so I want to see how she reacts to subtle hints.