Woocommerce: changed attributes of product variations

In a woocommerce website we have 2 attributes persons and destinations and 80 variable products (each one is the starting point of the excursion).

Persons is the number of persons a vehicle can hold (1-4, 5-10, 11-20, 21-50). So we created all the variations and add the prices. But customer asked to break 11-20 attribute to 2 values (he changed his vehicles’ types) so 11-20 is now 11-15 and 16-20.

Which is the best way to face this change? I thought that by exporting all the variations, delete them, create the new values for attribute persons, importing them back (with some csv manipulation) then I could just update the new variations prices. Is that correct? If so how I can regenerate all the variations for all variable products using all attributes without visiting every variable product one by one?

Is there an easier way and more efficient?