My two-year internet plan is ending in a couple months. How do I make sure my rates don't increase?

When I originally signed up with Xfinity two years ago, I was able to get the first two years at $55 per month, but that rate will increase once the initial two-year period has concluded.  I cannot afford an increased internet bill, and I see Verizon offers internet at this $55 price per month for my address, so if need be, I can switch to Verizon.  However, I'd prefer to remain with Xfinity, as I haven't had many issues over the past two years.  I am wondering what I need to do to make sure my monthly rates don't increase.  Can someone help me with this?