Lost weight, lost GERD symptoms, however, how frequently do I check the esophagus for any problems that could have been created by past reflux?

Depends. I there was no damage to the esophagus and it have no symptoms, no need to check it at all. If there was damage, particularly barrett's esophagus, may need surveillance every 2-5 years.
Look for symptoms. Look for the symptoms of acid reflux. There really isn't a good reason to do a test unless you are having symptoms.