When I select a schematic component, and right click to delete, then all connected wires and nets are also deleted. So switching out (replacing) one component with a different one requires all connecting wires to be redrawn. I suspect this is because scheme-it does not allow dangling wires.
@gortdb, Sorry for the late reply. You are correct. If a net starts with a component, that is the ‘anchor’ if you will, for the net. If you anticipate needing to swap out a particular part, be sure to start with a part you are fairly sure will stay. Another caveat is when running sub-nets/wires from your first net, if you delete the first net, all the others will disappear as well, but if you click twice on a sub-net, you can remove/alter that independently. If you click twice on a main net, you can also alter it’s color or line style independently from a sub-net.
Thanks for the question!