Absolutely! But we'll have to invoice you for our time. Typically, you'd contact us with the changes you'd like, we'd scope the project, and send you an invoice. Once you've paid, we'll put your project on the docket and get it done ASAP.
But honestly, depending on how many changes you expect to make over the year, you should upgrade to a plan that includes content updates. It could be more cost-effective for you.