Okay, couple of questions spring to mind.
1. Why haven't you seen her for 3 months?
2. Do you love her (a), like her (b) or just want to have fun with her (c)?
2a. If you love her, have a face to face talk with her and respond to her feelings. Try to find how how her words happened to come so out of blue.
2b. If you like her, try to find out if this is a prank or some kind wild idea gotten while drunk etc or if she is serious. If the first, laugh it off. If the latter, think of what you want from the future and if it includes her etc. In other words, think what you want from the future and discuss it with her.
2c. If she was kidding, nothing major here. If she is serious, this can only likely end in a heartbreak. Give her the news of your (lack of) feelings as gently as possible. If you have any respect for her, you will not string her along.