#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(?=Table \d+\.)"
Local $sString = "4 BLABLA\r\n Table 1. Real GDP\r\n Percentage changes\r\n 2016 2017 \r\nArgentina -2.5 2.7\r\nAustralia 2.6 2.5\r\n BLABLA \r\n Table 2. Nominal GDP\r\n Percentage changes\r\n 2011 2012\r\nArgentina 31.1 21.1\r\nAustralia 7.7 3.3\r\n"
Local $sSubst = "\n\n\n"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm