Long Distance Friends?

I moved a few months ago. I had to leave behind the best friend I have ever had. The thing is that she is more or less convinced that we won't keep in touch and that our friendship will fade. I've tried to show her it doesn't have to be that way. I only live a few hours away from her and we can see each other. There is also email (which we did regularly anyway) and cell phones. I am doing my best but it seems kind of one-sided at times. I'm the one doing the calling, the emailing and the driving. She has a family, but her children are grown and have their own lives and her husband does his own thing and they very rarely do anything together. I work a typical workday (7:30-4:30) and she only works until 1:00pm each day. It seems to me she has a little more time to invest in our friendship.

I'm very sad about this. Does she no longer want to be friends? Is she just using a self-fulfulling prophecy to prove that we can't be friends? I'm just not sure how to procede on this one. Good friends, true friends are so hard to find, but the signals I'm getting is that this one is indeed fading. How does one keep a long distance friendship strong?