How to update dojo tree data dynamically

I would like to know how ot update the data of the dojo.dijit.tree component dynamically. At the moment I'm creating the tree using dojo.data.ItemFileReadStore and dijit.tree.ForestStoreModel. Once I create the tree, I would like to reload it periodically with new JSON data.

This is how I create the tree at the moment:

<div dojoType="dojo.data.ItemFileReadStore" jsId="myStore" url=getJSONResult></div>

<div dojoType="dijit.tree.ForestStoreModel" jsId="myModel" store="myStore" query="{type:'cat'}" rootId="myRoot" rootLabel="Data" childrenAttrs="children"></div>

<div dojoType="dijit.Tree" model="myModel" labelAttr="sname" label="Data" />

Thanks in advance.