updating labels when switching dataset (+removing older one) - d3.js

Question

I've been drawing a planetarium with planets and labels on it :
svg.append("circle").attr("r", 20).attr("cx", w/2)
.attr("cy", h/2).attr("class", "sun");
svg.append("text").attr("x", w/2)
.attr("y", h/2).attr("text-anchor", "middle").attr("fill", "grey").text("VICTOR HUGO");
var container = svg.append("g")
.attr("transform", "translate(" + w/2 + "," + h/2 + ")")
var orbit = container.selectAll(".orbit")
.data(dataset, key)
.enter()
.append("circle")
.attr("class", "orbit")
.attr("r", 0);
//function(d) {return (d.key * ((w/2)/151) + 20); });
var planets = container.selectAll(".planet")
.data(dataset, key)
.enter()
.append("circle")
.attr("class", "planet")
.attr("r", function(d) {return 5;})
.attr("cx", function(d) {return d.x; })
.attr("cy", function(d) {return d.y; })
.on("mouseover", function(d, i) {
stopTooltip = false
showTooltip(d);
});
d3.select("svg").on("click", function(d) {stopTooltip = true;});
var texts = container.selectAll(".text")
.data(dataset, key)
.enter()
.append("text")
.attr("class", "text")
.attr("dx", function(d) {return d.x;})
.attr("dy", ".35em")
.text(function(d) {return d.titre});
Then, I've been adding a legend and a click function, so that when you click on one or another of the legend subtitle, the dataset is updated (if you look at the tooltips, it is indeed updated).
////////////////////////Legend//////////////////////////////////
update = function(newDataset, key){
var newplanets = container.selectAll(".planet").data(newDataset, key);
newplanets.enter().append("circle");
newplanets.transition()
.duration(0)
.attr("r", function(d) {return 5;})
.attr("cx", function(d) {return d.x; })
.attr("cy", function(d) {return d.y; })
.on("mouseover", function(d, i) {
stopTooltip = false
showTooltip(d);
});
newplanets.exit().remove();
var newtexts = container.selectAll(".text").data(newDataset, key);
newtexts.enter().append("text");
newtexts.transition()
.duration(0)
.attr("class", "text")
.attr("dx", function(d) {return d.x;})
.attr("dy", ".35em")
.text(function(d) {return d.titre});
newtexts.exit().remove();
}
var legendRectSize = 7;
var legendSpacing = 20;
var VictorHugoClass = [
{ "VHClassName": '...Auteur (oeuvre)', "VHClass": r990o, "color": "#0000FF" },
{ "VHClassName": '...Auteur (expression)', "VHClass": r990e, "color": "#FBA10D" },
];
//Initiate container around Legend
var legendContainer = svg.append("g").attr("class","legendContainer")
.attr("transform", "translate(" + 30 + "," + (h - 90) + ")");
//Create title of Legend
var legendTitle = legendContainer.append('text')
.attr('x', 0)
.attr('y', legendRectSize - legendSpacing)
.attr("dy", "1em")
.attr('class', 'legendTitle')
.attr('transform', function() {
var height = legendRectSize + legendSpacing;
var offset = height * VictorHugoClass.length / 2;
var horz = -2 * legendRectSize;
var vert = -2.3 * height - offset;
return 'translate(' + horz + ',' + vert + ')';
})
.attr("fill", "black")
.text("Victor Hugo en tant que...")
.call(wrap, 200);
//Create container per circle/text pair
var legend = legendContainer
.selectAll('.legend')
.data(VictorHugoClass)
.enter()
.append('g')
.attr('class', 'legend')
.attr('transform', function(d, i) {
var height = legendRectSize + legendSpacing;
var offset = height * VictorHugoClass.length / 2;
var horz = -2 * legendRectSize;
var vert = i * height - offset;
return 'translate(' + horz + ',' + vert + ')';
})
.on("click", function(d) {
update(d.VHClass, d.key);
});
//Append circles to Legend
legend.append('circle')
.attr('r', legendRectSize)
.attr('cx', 4)
.attr('cy', legendRectSize/2 - legendSpacing)
.attr("opacity", 1)
.style("fill", "white")
.style('stroke', function(d) {return d.color;});
//Append text to Legend
legend.append('text')
.attr('x', legendRectSize + legendSpacing/2)
.attr('y', legendRectSize - legendSpacing)
.attr("fill", "black")
.text(function(d) { return d.VHClassName; });
Nevertheless, the labels won't update with the planets, and some of the data of the former dataset are still remaining when the second dataset is loaded into the visualization. My Plunker is here for more details : http://plnkr.co/edit/UnhqCZhME7ymxdIbpcIj?p=preview
Thank you very much for your help in this...