Shopping cart (checkout) keeping only the last value

All right?

I'm working on a project with Laravel PHP framework for backend and jQuery for the front end. I'm setting up a football stadium ticket checkout for a system I'm developing.

I almost have all the checkout ready, however, what happens is that if I go back to <section> previous the value it calculates is the value of the product that it added, ie it does not keep the old value (the checkout is divided into 3 stages).

1 - The user selects the sector of the stadium and if he has a chair he selects the chairs he wants, if it is a bleach he selects the bleachers.

2 - The shopping cart with the products (He is calculating the quantity of products correctly but based on the type of sector that is). The problem is here. Briefly, I add 2 tickets that are in a sector that have chairs but then I go back and add another 1 ticket that is bleachers, if I go back to my cart he will calculate based on the price of the bleachers and not more on the price of chairs.

Print demo: link

In my jQuery, I am separating the values and it is calculating based on the response that comes from an AJAX from my database. In practice, the value it should bring would be 250.00 because in my database a chair costs 100.00 and a ticket for the grandstand is 50.00. But he brings only the last and the value of the chair is erased.

3 - Finally, the payment details.

My jQuey:

$('.btn-next a[href=#section-2]').click(function () {
let match = $('input[name=id_match]').val();
let sector = $('select[name=id_sector] :selected').text();
let id_sector = $('select[name=id_sector] :selected').val();

$('.checkbox-success').children('input:checked').each(function () {
    let chair = $(this).val();

    if (chair == ''){ chair = '-'; }

    // Monta a estrutura da tabela do carrinho de compras
    $.get('/api/checkout', {
        match: match,
    },
    function (data) {
        $('#data-cart').append('
            <tr>
                <td><p class="text-center">' + data['lot']['id'] + '</p></td>
                <td>
                    <div class="col-md-6">
                        <div class="col-md-4 text-center">
                            <img src="' + data['photo_club_main'] + '" style="height: 80px;"/>
                        </div>
                        <div class="col-md-4 text-center">
                            <img src="http://elotorcedor.local:8000/images/versus.svg"style="height: 40px;margin-top: 20px;margin-left: 20px;">
                        </div>
                        <div class="col-md-4 text-center">
                            <img src="' + data['photo_club_visitor'] + '" style="height: 80px;"/>
                        </div>
                    </div>
                    <div class="col-md-6">
                        <span class="col-md-12">' + data['championship'] + '</span>
                        <span class="col-md-12"><b>' + data['club_main'] + ' X ' + data['club_visitor'] + '</b></span>
                        <span class="col-md-12">' + data['stadium'] + ' - ' + data['date_match'] + '</span>
                    </div>
                </td>
                <td><span id="ticket-reserved" class="text-center">' + chair + '</span></td>
                <td><span id="sector-selected" class="text-center">' + sector + '</span></td>
                <td>
                    <select name="option_half" class="form-control">
                        <option value="1">Não</option>
                        <option value="2">Sim</option>
                    </select>
                </td>
            </tr>
        ');
    });

    $.get('/api/lot', {
        match: match,
        sector: id_sector,
    },
    function (data) {
        let elo_balance  = 80.00;
        let price_full = data['price_full'];
        let amount_chair =  $('.checkbox-success').children('[data-type=chair]:checked').size();
        let amount_grandstand =  $('.checkbox-success').children('[data-type=grandstand]:checked').size();

        if (amount_chair != 0) {
            var total = price_full * amount_chair;
        }
        if (amount_grandstand != 0) {
            var total = price_full * amount_grandstand;
        }

        var amount_pay = total - elo_balance;

        $('#amount-full').empty();
        $('#amount-pay').empty();
        $('#elo-balance').empty();

        $('#amount-full').append('<span class="money">R$ ' + total + '</span>');
        $('#elo-balance').append('<span>Saldo EloTorcedor: <b>R$ ' + elo_balance + '</b></span>');
        $('#amount-pay').append('<span class="text-success"><b>R$ ' + amount_pay + '</b></span>');

        $('.btn-next a[href=#section-3]').click(function () {
            let request = [

            ];
        });
    });
});

});

It's been a long time but I think the idea and problem is clear: x

If someone can give me a light or a way to correct, I'll thank you! Thanks guys;)