remove existing circles before adding new

src/plugin/depiction.ts

@@ -161,7 +161,8 @@ class Depiction {
         const firstScale = gradient.firstScale;
         const secondScale = gradient.secondScale;
         const thirdScale = gradient.thirdScale;
-        
+
+        this.weight.selectAll("*").remove();
         this.weight.selectAll()
             .data(data)
             .enter()