The collada scene contains more than just a mesh, but you can easily access the mesh within it.
To find the specific mesh you are looking for, try console.logging the collada object or setting a breakpoint in the load
function to inspect its contents.
To target the mesh located at collada.scene.children[0]
Within the load
function, save the mesh to a variable like window.referenceModel
window.referenceModel = collada.scene.children[0];
When you need to duplicate this model in the future
var refObject = window.referenceModel;
var clone = new THREE.Mesh( refObject.geometry, refObject.material );
// apply any transformations specifically to this clone
scene.add( clone );