I don't know of any specified limit, but I interpret the
AMA 2021 E/M guidelines that the decision for surgery risk may sometimes be counted more than once.
Specifically:
"The risk of complications and/or morbidity or mortality of patient management decisions made at the visit, associated with the patient’s problem(s), the diagnostic procedure(s), treatment(s). This includes the possible management options selected and those considered but not selected, after shared MDM with the patient and/or family."
Example: Progressively worse knee pain and documented that surgery is considered but not selected at one visit (patient opts for more conservative treatment with Rx and PT.) Returns in 8 weeks: pain is not improving, and now is proceeding with surgery. I would count the decision for surgery risk twice in that situation.
For your case, I think it depends why the surgery was not scheduled and why that patient is returning. If patient's medical history changed in the interim (for example, recently diagnosed with MS) and needs to discuss how this impacts whether or not she has the surgery, I would count it twice. If it was that she forgot the postop instructions, I would not count it twice. If she realized after going home that she forgot to provide a relevant aspect of her history, and she returns to discuss that additional information, I would count it twice. I would use the dividing line of whether or not to count it again as whether or not the clinician needed to make another management decision.