How to refresh layer with Leaflet/OSM

How do I refresh my heatmap with new data in a Leaflet/OSM environment?

I can successfully build the map using:
heatmap = new L.TileLayer.HeatCanvas...

and can load the map using:
for (var i in MapData) {
console.log('data');
heatmap.pushData(MapData[i][0], MapData[i][1], MapData[i][2])
}

My problem is I do not know how to clear the heatmap and load new data.

I have tried using heatmap.clear(), but this seems to have no effect as everytime I push data into the heatmap it simply adds to the existing data.

Does anyone know how to basically clear the data from a heatmap, load new data in, and redraw the map?

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