Test case:

<canvas debug="true">

    <dataset name="ds">
        <item name="one"/>
        <item name="two"/>
        <item name="three"/>
        <item name="four"/>
    </dataset>

    <simplelayout/>

    <button text="add new item">
        <handler name="onclick">
            ds.appendChild(new LzDataElement("item", { name: "NEW ITEM"}));
            Debug.write('ds childNodes:', ds.childNodes);
        </handler>
    </button>

    <view id="list" layout="axis: y">
        <replicator name="rep" dataset="ds" xpath="'/item'">
            <view>
                <text datapath="@name"/>
                <handler name="onclick">
                    this.data.parentNode.removeChild(this.data);
                    Debug.write('ds childNodes:', ds.childNodes);
                </handler>
            </view>
        </replicator>
    </view>
</canvas>


Also, shouldn't you be able to set datapath="dset:/somexpath"?