Until you get concrete proof that she has done more than just kiss you are going to have to believe her and work on your relationship. You have a long distance relationship so it's going to be hard to trust her completely and believe that when she gets lonely she will not go out and meet other guys. A good start would be to go up there tonight and see if the relationship can be salvaged. You might have to start all over and start with dating and getting that trust back but she has to work towards that also. Long distance relationships have both, advantages and disadvantages. For some, the distance is a good thing to help you to slowly open up to the relationship without the constant presence of the partner. The romance stays kindled because you aren't around the person everyday or all of the time seeing various habits and routines that can get repetitive, the disadvantages are, it is very frustrating that there is no intimacy, no hugging, no kissing. You will experience difficulties in connecting because you don't have eye contact and can't take walks or enjoy each others company and that is one of the problems you are having with your girlfriend not being able to see or spend time together but you both have to make time for each other if you expect the relationship to work.
Communication is key and that is something your girlfriend is going to have to work on since she is the type that doesn't show affection. You have to communication what is wrong in the relationship and then you both be willing to work on that together there are other ways of contacting her like phone, internet, letters, text messaging. Don't take for granted that she is going to be there waiting for you when you are ready. You have to show her that she still means as much as she did before to you or else she will get lonely really fast and will look for that attention from someone else. Start by going to be with her tonight and then on the float and just enjoy each others company and try to rekindle the relationship and then take it from there.
You don't want to look later down the line at your life and have any regrets so if having her back in your life is what you want then you should fight for that. She has already told you that she wants to get back together but she doesn't know when then that means that she isn't ready for a long distance relationship and how hard it can be but if the two of you try to work things out together but if you aren't ready and don't feel that you will be able to trust her and that she isn't willing to fight for the relationship now then it may not be a good idea for you to go there on a friends basis if it hurts to go there knowing you are only friends. She has a lot of issues she has to deal with before you can get back together so I would allow her time to make those changes and if she does not then maybe you should move on until she matures enough to stay faithful and not kiss other men when she gets lonely. I suggest you both take a break for a while so that you both can think about what it is you want and with whom do you want it with.
I would only suggest you going if you can separate your feeling and not want romance when she wants friendship for now. If you think there is a chance to get her back by going there then do so but if you think when you go there that things will not change then don't set yourself up for that heartache.