So my ex is moving to New Zealand in a few weeks she's doing her phd over there so will be there for a least 2 years. We Haven't really been in contact much the last months but I kinda still like her a lot. Should I message her to ask her to say goodbye in person?
Hmm, that's tough. Seeing each other will probably make things a lot harder for you. Either way, I don't see how it could end well. She could 1) reveal she still has feelings for you as well (and then she leaves?); or 2) not want to meet at all; or 3) meet you and you find out she has no feelings. Either way, not very good options.
That being said, you should live life with no regrets. If you think you'll really regret not saying goodbye, then you should go for it. But I don't think you should stir up old feelings for a girl you "like a lot".
If you're still on good terms with her, then yes, I would say to go ahead and ask her for coffee or something. Just say "hey, I'd like to see you before you leave for N.Z. how about some coffee?" or something like that. That's only if you're on good terms with her now and have talked to her at some point since you broke up. If you haven't really talked to her or anything, then it's probably not a good idea.