$re = '/\),[^\S\n]*(?=\w)/m';
$str = 'text cat dog cat dog
),
text rabbit cat dog
), text coffee cat dog. #need to indent this line';
$subst = "),\n";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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 PHP, please visit: http://php.net/manual/en/ref.pcre.php