Month to Month Lease Legality

[Victor Olowu]

My tenant has been in the unit for 2 years now, but during this past year, she lost her job and I believe got another one.  She hasn't missed any payments, but to be on the safe side, I am having her re-qualify, i.e. income/work verification, to make sure her new income still meets my cutoff ratio.  Also, instead of renewing for a 3rd full year lease, I want to put her on a month-to-month lease which should help if she has issues making the rent.  

Summer is ending though, so I want to put a freeze in the lease between November and February where she can't move out, and I would not change the rent etc.  Should I just add an addendum to a standard month-to-month lease (which I don't even have yet because I don't usually do month-to-month leasing)? Is there a problem putting a freeze in your lease terms?