ChartView {
        id: chart
        ....
        property var type: "Type 1"
        LineSeries {
            axisY: CategoryAxis {
                min: 0
                max: 30
                CategoryRange {
                    label: "critical " + chart.type
                    endValue: 10
                }
                CategoryRange {
                    label: "low "+ chart.type
                    endValue: 20
                }
            }
            XYPoint { x: 0; y: 4.3 }
            XYPoint { x: 1; y: 4.1 }
            XYPoint { x: 4; y: 5.2 }
        }
    }

    Button{
        text: "change sensor"
        onClicked: chart.type = "Type 2"
    }