Bill went up by $30

I was paying 70$/mo and since the contract ended the bill is up to 100$/mo (24mo contract). Looking at the current deals, I can enter another contract for my existing plan at 90$/mo for a year. But if I were a new customer there is a deal for 70$mo (36mo contract) for this plan. Is there any way to get the new customer plan? Can I cancel my service and sign up again as a new customer?