You can't get back to CBR from MK via lyft unless you get a MinnieVan. The only transportation from MK are Disney Busses, Boats, Monorails and the MinnieVans operated by Lyft.
Since you will first have to get to the TTC and then take a lyft or uber it doesn't seem worth it to me.
You can open the lyft app and put in your destinations even if you are not near MK. Right now it is showing $51.02 for a MinnieVan from MK at 3:54 dropping off at Building 54-56, or from TTC $10.87 on a normal Lyft.