add the Line.mode property for serializing THREE.Line objects maybe there is a better way to implement it, this is quick and dirty.
@@ -698,6 +698,11 @@ THREE.Object3D.prototype = {
data.geometry = parseGeometry( object.geometry );
data.material = parseMaterial( object.material );
+
+ if(object instanceof THREE.Line){
+ data.mode = object.mode;
+ }
} else if ( object instanceof THREE.Sprite ) {