How do I prove her that I am serious?

So my girlfriend broke up with me after 1.6 years of dating because she asked me 6 times or so to make her feel loved and appreciated but I didn't. She wanted me to take her star gazing on walks for a picnic and to call her more to bring her flowers randomly and write sappy love notes. She didn't want me to be her slave she just wanted to feel more appreciated and for me to show that I actually cared for her. So how do I prove to her that I'm absolutely 100% dead serious this time? How do I prove to her that I will change my way of doing things and would do anything to make her happy feel loved and appreciated. How to I prove to her that I'm absolutely 100% dead dead dead dead serious that I will change in that retrospect. How do I prove to her that I'm willing to go to the ends of the earth to prove to her that I will do these things after I've let her down so many times? She means the world to me and I don't wanna lose her for good I just want a chance that I don't deserve to prove to her that I will do all the things mentioned in the beginning and more. How do I make her see that I'm telling the truth though she doesn't believe me? Were are apart ATM and she won't let me come see her only text her or call her how do I prove this to her by word of mouth?