No good way. The problem is after the connection error your printer probably restarted.
That means it has no idea where your printhead and your bed is located at the moment.
So you would have to calibrate it without homing (I don't even now if that's possible) and start a new print mid air which starts at the point where the old one stopped.
TL;DR - no
Try to encase the mainbord box with something like aluminum foil (but keep the fan holes open)
It is not possible that the printer restarts because as written I can work from SD-Card while my wife is working on the sewing machine. She was working for more than an hour on the machine while the printer was doing its print job.
That means - whatever it is - it has influence on the USB-connection but not on the rest of the printer.
It remains cabel, Pi, Pi-Power or only the USB-interface of the printer.
Big motors like you might find in compressors (air conditioner, refrigerator) or in things with a flywheel mechanism (sewing machine) pull large amounts of current on their startup phase. You could probably also recreate this problem with an old-school kid's racetrack with the hand-held yellow trigger devices.
So when "big current" is needed, it pulls that from the mains. The net result is that everything else sees a reduction of the voltage. In my case here, a voltmeter in any outlet would go from the expected 120VAC down to perhaps 106VAC over a short period of time.
Next up, the power adapter for the Pi has a transformer which is a simple device. There is a ratio of coils of wire which is preset and that ratio is calculated for 120VAC being on the primary side of that. So when that's less, the output side is less by the same percentage and the Raspberry Pi is suddently in an undervoltage condition. The logical threshold which determines the difference between a one and a zero is now lower than where it's supposed to be and serial communications are trashed.
Solution: Plug your 3D printer into a UPS and call it a day.