No need to cancel right now. If there are weather issues, or other problems, you may be able to cancel and get a full refund. If you cancel right now, you won't be eligible for a refund if there are problems later.

But you do need to cancel at some point. Not sure what the cut off is, but it needs to be before the scheduled departure time. After that, as others have said, you can schedule a new trip, but you'll have to pay the $200 change fee.

Think of it this way. Over the long run, you'll save a lot of money buying non-refundable tickets. Every now and then, something happens and you have to pay $200. Overall, you're still way ahead.