I don’t think I totally understand the situation. What was the date of the last note requesting the 3-month accommodation extension? If you’re suggesting that it was more than 3 months ago, then, yes, the justification for the accommodation has expired. That doesn’t necessarily mean the NEED for the accommodation has expired. What’s required is a revised evaluation based on the current circumstances. You need to get back into communication with the employee and do the reassessment.
If the doctor’s note was more recent than 3 months ago, then it would still seem to apply. Again, I’m just not exactly sure what the situation is. Feel free to follow up.