Since SW decided to dispose of SW Explorer, how do we update/change external references now?

Ex. 

I have a route assembly that references a mother assembly. The mother assy has changed to Rev. 1, and I want the route to reference the new Rev. 1.

In Explorer it was easy as the mother assembly would be listed under references. Now if I look at external references of the route, the mother is listed up above but, you can't edit it.

also,

We do not use a PDM.