We don’t know any other way to create variations with different prices without creation variations. You can use bulk edit of the variations price http://prntscr.com/q8fdvn
You can ask WooCommerce plugin support about other ways, maybe they will suggest you something. This option is not our theme option, it’s WooCommerce default functionality, so we can just tell you the default instructions from the plugin developers described in documentation https://docs.woocommerce.com/document/variable-product/
