What are the steps to renew a retirement visa in Thailand and add a trailing spouse on a Non-O visa?

as people said you can't "add your wife" to anything, she'd have to find a thai consulate in another country that would issue the 90 day Non-O visa to based on her being married to a foreigner on a long term retirement extension.

At this time Penang Malaysia might do it, BUT only if she shows that you have a long term extension.

As far as when you can apply for a new year extension at most offices you can do that when you have 30 days or less left on your current stamp. So you can go any time after June 23 for your next yearly extension

Your wife will need to get herself on a Non-O visa for a trailing spouse, which she can't get inside Thailand, before this can happen.