$re = '/(\{|,)\"(?!slug).*?\"/';
$str = '[{"id":"0","title":"Testowy post Laravela","subtitle":"","author":"Marcin","content":"Tekst nr 4","slug":"testowy-post-laravela-4","created_at":"2014-11-02 10:30:42","updated_at":"2014-11-02 10:30:42"},{"id":"1","title":"Testowy post Laravela","subtitle":"","author":"Marcin","content":"Tekst nr 0","slug":"testowy-post-laravela-0","created_at":"2014-11-02 10:30:42","updated_at":"2014-11-02 10:30:42"},{"id":"2","title":"Testowy post Laravela","subtitle":"It\'s a rocket!","author":"Marcin","content":"Tekst nr 1","slug":"testowy-post-laravela-1","created_at":"2014-11-02 10:30:42","updated_at":"2014-11-02 10:30:42"},{"id":"3","title":"Testowy post Laravela","subtitle":"","author":"Marcin","content":"Tekst nr 2","slug":"testowy-post-laravela-2","created_at":"2014-11-02 10:30:42","updated_at":"2014-11-02 10:30:42"},{"id":"19","title":"Testowy post Laravela","subtitle":"","author":"Marcin","content":"Tekst nr 3","slug":"testowy-post-laravela-3","created_at":"2014-11-02 10:30:42","updated_at":"2014-11-02 10:30:42"}]';
$subst = "";
$result = preg_replace($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