net profit ratio increases by generating more sales or controlling expenses more effectively.
in terms of generation of sales you could have a few different responses:
Increase mark up while keeping cost price constant, decreasing mark up while keeping cost price constant, an advertising campaign, improvement of stock mix to improve suitability to customer, etc
controlling expenses could fall under COGS:
- stock loss
-cost of sales
to control these mgmt may seek a cheaper supplier. Also mgmt may also investigate the reason for stock loss and may implement security measures, train staff for stocktaking methods, etc
in terms of other expenses:
wages
advertising
etc
etc
these are subjective to the question but i normally say an investigation in the increase of expenses may be undertaken by mgmt to find the problem area and take necessary remedial action.