Windows: setData does not add UI elements that already existed

var _window = Ti.UI.createWindow({ backgroundColor: 'green' });

var data = [];

var row = Ti.UI.createTableViewRow();

var lbl = Ti.UI.createLabel({

    text: 'label'

})

row.add(lbl)

data.push(row);

var table = Titanium.UI.createTableView({

    top: 100,

    data: data

});

var btn = Ti.UI.createButton({

    title: 'Add new data',

    top: 5

});

btn.addEventListener('click', function() {

    var newData = [];

    var newRow = Ti.UI.createTableViewRow();

    var newLbl = Ti.UI.createLabel({

        text: 'label again'

    })

    newRow.add(newLbl)

    newData.push(newRow);

    table.setData(newData)

});

var oldbtn = Ti.UI.createButton({

    title: 'Add old data',

    top: 50

});

oldbtn.addEventListener('click', function() {

    table.setData(data)

})

_window.add(btn);

_window.add(oldbtn)

_window.add(table);

_window.open()