Believe it or not, but that is her way of keeping in touch. It's kinda like - nudge, nudge just letting you know I know you are still alive and so am I. Unfortunately, the things that are said during those harmless interactions is as Scary Guy said, "One person is always going to care more than the other."
Although you have gotten used to using a catchphrase to deal with it, don't lose heart. Make each conversation feel equally important and appear to be separate and stand on it's own. In her head, she is reaching out to you and showing that she cares. To you, it may seem like empty promises never to be fulfilled.
During my college years, I had gotten that way with one of my aunts. We would speak on the phone and I knew there was work she wanted me to do for her, but I also knew that my studies wouldn't allow for it. So during our conversations, I would mention those little projects so she would know that I hadn't forgotten about them and the call always ended with some talk of a future visit. I am glad that time did eventually permit me to get back over to see her and do some projects around her house for nowadays, she is very ill and fragile and living on oxygen which is very different from the strong, independent woman I have known my entire life.