New York (CNN Business) Super-loyal customers who use Starbucks' membership program account for about 40% of sales at the company's US stores. Now Starbucks is taking steps it believes will make the program more attractive.

Starting on April 16, the coffee company's rewards members in the United States and Canada will start earning rewards sooner and have more options when redeeming points. For customers who use a Starbucks rewards credit or debit card, points won't expire. (They still expire after about six months for other members.)

Starbucks SBUX Digital rewards programs are a way for companies such asto increase loyalty and learn more about their customers. The update is designed to bring even more people into the program by offering more choice.

The current rewards program works like this: Customers get two points, or stars, for every dollar they spend. Customers need to hit 300 stars within one year in order to start qualifying for rewards. Once they qualify, they can get a free drink or free food for every 125 stars. If they hold on to the points until they reach, say, 250, they can redeem the points for two free drinks, two food items or one of each.

The new system lets people get different rewards for different amounts of stars, and starts at a lower tier. Members can cash in 25 stars for an extra espresso shot, dairy substitute or another flavor pump. For 50, they get coffee or tea or a bakery item, and so on.

Read More