I also always leave the country after extension before my 90 day report is due. Last year after re-entry I did my 1st 90 day report in person. But this year after re-entry end of September I registered for online reporting and just today did my 1st 90 day report online 14 days before it was due. It was approved in about 3 hours. So it therefore does not need to be done in person every time after re-entry.