Hello Manuel,

I have written a scheduled action which should achieve what you are after.

# get all in draft stage and have the split_method equal
all_items = env["stock.landed.cost.lines"].search(["&", ("cost_id.state", "=", "draft"), ("split_method", "=", "equal")])

for item in all_items:
    item["split_method"] = "by_current_cost_price"

I would suggest trying this on some test data first, as I have only tested this briefly. 

Thanks,