I’ve been trying to do the same thing. Unbelievably, it seems there is no way to do this. I have over 200 existing products, all with the same variants and prices, and if I want to change my prices its seems I have to go through each one individually and do it manually. I have also added some new framing options, and want to copy them to all existing products. It blows my mind that there is no simple way to do this.
Surely people change their prices every now and then?