LPT Request: How to get out of commitments with no planned date

My neighbor wants to be besties, but I'm not interested in being more than neighborly. She keeps suggesting 'let's do a movie night" and asks when it works for me. I don't want to commit to anything and I can't say I'm busy forever, so how can I get out of plans that haven't had a date established? I just don't want to be involved in the plans at all.