If you want to reset the widget you should read the first page of its dataSource and reset its scroller. For example:
listview = $(
//request the first page
//reset the scroller
In case you want to clear the DataSource (e.g. no information to be displayed) you should create a new DataSource instance and set it through the setDataSource method.
The scroller have to be reset too.
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI