What are the most effective ways of making your girlfriend more affectionate?

I was at the local neighborhood pool with my girlfriend, and we were all having fun, and then I picked up my girlfriend on the steps but I lost my grip and she slipped and fell. She pushed me away so I walked away (stupid decision) and she says quietly "I wanna break up". So I froze, and then I ran over to her and got her to give me another chance. She's going to New York tomorrow and she won't be back for a week and a half, and I would like to know something that'd make her love me again. Any ideas?

Edit: She said she legitimately loved me, not just saying to say it but she meant it We've been like best friends for months, then we started dating when we were still like best friends, and she was completely fine before that slip. And booze isn't an option, I will not disclose our exact age in risk of being ridiculed but my fellow redditors.