Maybe you should tell her why this time is different than before. I'm sure she's convinced that you only want her back because she's moved on and is less available to you. Obviously, you can't promiser her anything (there are no guarantees in life) but maybe communicate something to her about how and why you suddenly realized you were still in love with her again. Please realize that she didn't change everything you had for someone else...you broke up with her (not the other way around)...she simply moved on after a year of telling you that she missed you. To me, it just sounds like you want what you can't have but, to get her back, you'll probably have to convince her that this is not true and that you honestly do love her. But, do not even go down this road if you're just reacting to her moving on....that would be incredibly selfish and you'd only end up breaking her heart again and I can't imagine any friendship could be salvaged from round two.