Is a new lease required when raising rent?

[Dan Rosen]

I have some long-term tenants who are month-to-month, and I've never raised their rent. I need to raise it now, since it's significantly below market. Two questions about this:

* Does raising rent require signing a new lease?

* Their utilities (gas and electric) are currently included. I want to transfer that responsibility to them as well. Does that require a new lease?

Thanks!