When I'm doing a new or revising a route I always create or move it to a new list I have named "New Maps Here". When you do that, it will only show a single route or the routes you have in there. When you change the route, it will change globally also. When you want to do this just click on the existing route from the list and hold the Control Key when moving a copy to the new list. That will keep the route in both lists. When you want to remove a route from the new list Right Click on the route and select Remove from New Maps Here. That will still leave the original map in the List Folder.
If you want to keep the old route as is just make a duplicate of it and follow the above instructions.