Price change

Goal: I would like to offer an "introductory price" of $99.00/year. Say, 6 months later, I would like to then offer my "regular price" at 125.00/year.

Question: do I simply just change the plan price and they will automatically be charged $125.00 instead of $99.00 when it is time for them to renew? Or would I have to use a coupon code at the beginning to bring the price down to $99.00? I would like to avoid using a coupon code.

Thanks so much!

Aaron