I have a bad tenant who bounces checks and replaces them later, effectively giving me rent 20 days late. The lease calls for a penalty, but she does not pay it. Her dog kills chickens and bites people. She had a one year lease, but is now month to month. I don't want to evict her until better weather, to avoid a vacancy now when it will be difficult to fill, but don't want to put up with the bounced checks and her dog. Can I give 20 days' notice to change the terms?