Maybe something like this?
#include <Excel.au3>
; Pass the following parameters:
; * Object of the Workbook
; * Number or Name of the Worksheet
; * Name or Index number of the table
; * Name or Index number of the Column
Func FindLastRowInExcelTable($oWorkbook, $vWorksheet, $sTable, $iColumn)
Local $xlByRows = 1 ; Searches across a row, then moves to the next row.
Local $xlPrevious = 2 ; Search for previous matching value in range.
Local $iLastRow, $oWorksheet, $oTable
$oWorksheet = $oWorkbook.Sheets($vWorksheet)
$oTable = $oWorksheet.ListObjects($sTable)
With $oTable.ListColumns($iColumn).Range
$iLastRow = .Find("*", .Cells(1), $xlFormulas, $xlPart, $xlByRows, $xlPrevious, False).Row
EndWith
EndFunc ;==>FindLastRowInExcelTable