[Solved]-change data point value inside load event in HighCharts-Highcharts

You can easily use this.series[0].update:

this.series[0].update({
                    data: [
                        {y:10,x:1},
                        {y:7.5,x:2},
                        {y:9,x:3},
                        {y:7,x:4},
                        {y:7,x:5},
                    ]
                });

This will automatically redraw the chart and update the data: DEMO

Or you can use this.series[0].isDirty = true before calling redraw:

load: function () {
                this.series[0].data[1].y=7.5;
                this.series[0].isDirty = true;
                this.redraw();
            }

Here's the DEMO