This option is not available in the desktop application. The solution is to update the list via the API — you can find the price list tree structure here.
Description of tree fields: https://demo.flexibee.eu:5434/c/demo/strom/properties
To move a branch, you need to update the otec element = the ID of the new parent category, the cesta element = the same as for a branch at the same level, and the pořadí element = set it to e.g. 99 to be safe, which will place it at the end.
This will move the entire category including its subcategories — not copy it.