Usually, a "renewal ride" is not going to be as rigid as a CFI intial. FOI's should not be required on a renewal (see the PTS), but it might not hurt to bone up a little.

Also, you may renew your CFI by taking a checkride for any rating on your original CFI ticket. Assuming that you had a CFII, a CFII ride is much simpler to prepare for compared to a CFI-Airplane. Most folks take the CFII ride.

Usually the examiner will go easy on you, assuming that your original CFI isn't 30 years out of date.