Nope, you can't replace the rotors without having to reset the bearings. Essentially the bearing comes apart as the hub, which the rotor is attached to, comes off the spindle.

Loosening the bolts that hold the rotor to the hub is a major PITA. Heat and a lot of torque are your friends. Some folks reattach the hub to the road wheel when the hub's off the spindle to have something to hold while loosening those bolts.

You should replace the inner bearing seal anytime the hub comes off the spindle. If you don't have service records suggesting the wheel bearings were serviced recently, or at all, plan on cleaning and repacking the wheel bearings. You can't go wrong with MB label green wheel bearing grease and it's conveniently packaged in a front axle's worth quantity.

Sixto
87 300D