Updating Google Maps bookmarks every 10 seconds!

Friends, I made a system to record the points in the DB and then display them on the map. It is working normally, but as I did the BD via ajax, the page is not updated!

I'm doing it this way, but updating the whole page:

//Gravar os dados no SQL, via AJAX
$('#formulario').submit(function() {
    var form_data = new FormData();
    form_data.append('arquivo', $('#arquivo').prop('files')[0]);
    form_data.append('txtLatitude', $('#txtLatitude').val());
    form_data.append('txtLongitude', $('#txtLongitude').val());
    form_data.append('txtObs', $('#txtObs').val());

    $.ajax({
        url: 'cadastrar.php', // caminho para o script que vai processar os dados
        type: 'POST',
        data: form_data,
        cache: false,
        contentType: false,
        processData: false,
        success: function(response) {
            $('#resultado').html(response);
            $("#resultado").fadeTo(3000, 500).slideUp(1000);
            $('input').val('');
            $('textarea').val('');
            setTimeout(function(){
                window.location = "principal.php"
                },5000);
        },
        error: function(xhr, status, error) {
            alert(xhr.responseText);
        }
    });
    return false;
});

To load the points on the map, from PHP, I'm using the following:

function carregarPontos() {

var json = <? echo $JSON ?>;

    $.each(json, function(index, ponto) {

        var marker = new google.maps.Marker({
            position: new google.maps.LatLng(ponto.latitude, ponto.longitude),
            title: "Meu ponto personalizado! :-D",
            map: map,
            icon: ''

        });
        var infowindow = new google.maps.InfoWindow(), marker;

        google.maps.event.addListener(marker, 'click', (function(marker, i) {
        return function() {
        infowindow.setContent("<img width='80' src=" + ponto.foto + "><br>Foi visto: " + ponto.obs);
        infowindow.open(map, marker);
}
})(marker))

    });
}

carregarPontos();

How would I do to be able to update the div with the new added point soon after insertion of the data?

Thank you in advance!