You could try a .QXF (X in the middle) export, create the new file and import the .QXF file into it.. This is all on the File menu.
The only thing you will lose is your time if it doesn't work well enough. Your current data file will not be harmed in any way.
Note thta a .QXF import will not import investment transactions. If you want to try QIF instead here is some help on that:
https://www.quicknperlwiz.com/changetransfers.html
But before any of that I would first try: Copy or Backup File → Create a copy or template
This might be enough to clean up some problems. Note that it will disconnect all online services, so you will have to reconnect them in that new data file.