How can I renew a licence that has been expired for a year?

Forget about going to the DMV website. Phone a DMV office in your state, and ask them how you need to handle this. The DMV office might be closed tp walk-in customers, but there will be someone in the office  who will answer the phone and answer your questions. 

You should be getting a break in the timing because of the virus. My state is allowing drivers with expired licenses to drive because the DMV was closed, and no--you can't renew it online. Call the DMV. They have rules in place for this problem. 

However--your license expired LAST year--not this year. Why didn't you renew it then? The virus wasn't the issue then. You let it go for a year?  If you've been driving all this time, you've been breaking the law--and if that's what you're worried about, then you have a bigger problem. You still need to call the DMV. 

You can't "renew" something that no longer exists.

In my state, you'd go down to the dmv and pay the fine, penalties & back taxes.

If your dmv is closed, you hurry up and wait.

You went online and it didn't give you the option of renewing. To me that would mean you start all over

You ask DMV.  They got their rules.

That depends on your state.  All I found for WA state (where I live) is that additional fees may apply but I couldn't find an amount (not that they would apply to you unless you are in WA state) or how long past the expiration date it can be.

You can't renew it you have to start all over again.😉

Most states are now taking scheduled DMV trips, you need to call and schedule an appointment, you have to go in when its been expired that long. 

Good Luck,