What are my options if my extension for a non-immigrant O visa is not granted in Thailand?

Sounds like you are applying for a 12 month extension of stay for retirement. You either meet the criteria for both the current year and the next year or you don't. There's no real leeway. If you are refused you can leave Thailand and return visa exempt and start over by applying for a new 90 day Non-O and then an extension or apply for the 90 day Non-O at a nearby consulate then extension before that expires

@Mike ******

if this is your second, or longer, year extending your extension of stay, you must have at least bt65,000 deposited from an overseas source every month with no exceptions. You can not be short one month, and be over the next month to make up for it. It is not a cumulative total over the whole 12 months. It is at least bt65,000 every month. If one month is short then the 12 month count restarts the following month. If that happens then the bt800,000 sum in the account for at least two months is again required, as the US embassy does not issue notarized wage statements that is the only other thing immigration accepts.

As long as your ducks are in a row you should have no problem,Bank Statements bank book ,TM30 lease it’s easy

If you meet the requirements there’s usually no reason an extension won’t be granted.

Depends on your nationality as to whether you can leave and return quickly (without a visa).