Edit in JSFiddle

var data = [
    ['Tokyo', 7.0, 6.9, 9.5, 14.5, 18.2, 21.5, 25.2, 26.5, 23.3, 18.3, 13.9, 9.6],
    ['New York', -0.2, 0.8, 5.7, 11.3, 17.0, 22.0, 24.8, 24.1, 20.1, 14.1, 8.6, 2.5],
    ['Berlin', -0.9, 0.6, 3.5, 8.4, 13.5, 17.0, 18.6, 17.9, 14.3, 9.0, 3.9, 1.0],
    ['London', 3.9, 4.2, 5.7, 8.5, 11.9, 15.2, 17.0, 16.6, 14.2, 10.3, 6.6, 4.8],
];

var update = function (obj, cel, val) {
    // Get the cell position x, y
    var id = $(cel).prop('id').split('-');
    // If the related series does not exists create a new one
    if (! chart.series[id[1]]) {
        // Create a new series row
        var row = [];
        for (i = 1; i < data[id[1]].length; i++) {
            row.push(parseFloat(data[id[1]][i]));
        }
        // Append new series to the chart
        chart.addSeries({ name:data[id[1]][0], data:row });
    } else {
        // Update the value from the chart
        chart.series[id[1]].data[id[0]-1].update({y:parseFloat(val)});
    }
}

$('#my').jexcel({
    data:data,
    onchange:update,
    colHeaders: [ 'Country' ],
    colWidths: [ 300 ]
});

// Kepp it global
var chart = null;

$(function () {
    chart = Highcharts.chart('container', {
        title: {
            text: 'Monthly Average Temperature',
            x: -20 //center
        },
        subtitle: {
            text: 'Source: WorldClimate.com',
            x: -20
        },
        xAxis: {
            categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
                'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
        },
        yAxis: {
            title: {
                text: 'Temperature (°C)'
            },
            plotLines: [{
                value: 0,
                width: 1,
                color: '#808080'
            }]
        },
        tooltip: {
            valueSuffix: '°C'
        },
        legend: {
            layout: 'vertical',
            align: 'right',
            verticalAlign: 'middle',
            borderWidth: 0
        },
        series: [{
            name: 'Tokyo',
            data: [7.0, 6.9, 9.5, 14.5, 18.2, 21.5, 25.2, 26.5, 23.3, 18.3, 13.9, 9.6]
        }, {
            name: 'New York',
            data: [-0.2, 0.8, 5.7, 11.3, 17.0, 22.0, 24.8, 24.1, 20.1, 14.1, 8.6, 2.5]
        }, {
            name: 'Berlin',
            data: [-0.9, 0.6, 3.5, 8.4, 13.5, 17.0, 18.6, 17.9, 14.3, 9.0, 3.9, 1.0]
        }, {
            name: 'London',
            data: [3.9, 4.2, 5.7, 8.5, 11.9, 15.2, 17.0, 16.6, 14.2, 10.3, 6.6, 4.8]
        }]
    });
});
<script src="https://code.highcharts.com/highcharts.js"></script>

<div id="container"></div>

<br>

<div id="my"></div>