D3: How to refresh a chart with new data?

Create one function that (re)draws the pie when it’s created and when it’s updated.

New data should be added to pie using enter() and old data should be removed using exit().remove()

It is as simple as this:

  path.enter().append("path")
            .attr("fill", function(d, i) { return color(i); })
            .attr("d", arc)
            .each(function(d) {this._current = d;} );

  path.transition()
            .attrTween("d", arcTween);

  path.exit().remove()

Full working code -> JSFIDDLE