Sometimes all it takes a little preparation, getting out of the house, and writing a huge check to a charity you hate...
These are a few ways to keep a conversation going I learned wandering around the streets of NYC talking to strangers.
The first thing you can do to keep a conversation going is to tell a story - have a few practiced and ready to go. You can also ask open ended questions that you actually want to know the answers to.
You already know how to keep a conversation going if it's about topics you have passion for, so ask questions that drive the conversation back to those things.