Dojo Tree.refresh

extendTree.js

require(["dojo/_base/lang", "dijit/Tree"], function(lang, Tree){
  lang.extend(Tree, {
    refresh : function() {
        // Destruct the references to any selected nodes so that 
        // the refreshed tree will not attempt to unselect destructed nodes
        // when a new selection is made.
        // These references are contained in Tree.selectedItem,
        // Tree.selectedItems, Tree.selectedNode, and Tree.selectedNodes.
        this.dndController.selectNone();
    
        this.model.store.clearOnClose = true;
        //this.model.store.close();
    
        // Completely delete every node from the dijit.Tree     
        this._itemNodesMap = {};
        this.rootNode.state = "UNCHECKED";
        this.model.root.children = null;
    
        // Destroy the widget
        this.rootNode.destroyRecursive();
    
        // Recreate the model, (with the model again)
        this.model.constructor(dijit.byId("myTree").model)
    
        // Rebuild the tree
        this.postMixInProperties();
        this._load();
    
    }
  });
});

// then you can call
tree.refresh();