Domain names renewal fees are normally NOT included in the hosting renewal fees.
However, there are some cases in which you may not be charged a renewal fee for a primary domain, as it was acquired as a part of a special hosting promotion.
When a domain name renewal fee is due, you will see your domain listed in your Client Area -> Invoices -> Unpaid.
If the domain name is registered by another registrar, you should contact them directly and ask them for assistance.