How to raise regular prices by 15% with a WooCommerce bulk price change

Yes! A WooCommerce bulk price change can raise or lower regular prices relative to their current value.

Select products using checkboxes or filter them by any parameters you need
Open Bulk Editor form
Find field 'regular price' and check it by checkbox near
Enter 15 in the textinput and in the drop-down near it select 'increase by %'
Click on 'Do Bulk Edit' and wait while the operation finish