Offer them the following: they can get the product they chose for the regular price, or they can buy another product (either the same or another) and get a nice discount for both, but only if the second one is going to be a gift for someone. If it’s a consumable, you might want to have a permanent sticker on it saying “A gift to X from Y – brought to you by YOUR BRAND NAME” so they are more likely to gift it. If it’s not and it’s the same product (like two copies of the same book), then that is optional.
In any case, even if they don’t gift it, it will still help grow your transaction size. If they do, it will also help you spread the word about you and the product.
By looking at the demographic and psychogenic markup of your current customers, you can find out other things that a large part of them are in-market for. Things that interest them or they are looking to buy.
You find such an interest area that does not contradict your brand, and find good partners in that field. Invite these partner(s) to do an event with you at your store.
Your customers will appreciate it (the large group that is interested.) The partner will like the new business and clients they get. And you’ll get a commission on sales from the partner.
For the tweens and teens, it’s an opportunity to see how working works and show they can do more. For retailers, it’s a chance for publicity and showing potential future workers it can be a good career.
Have the young adults apply for different jobs at the stores. Interview them and pick the ones that fit. Then train them little by little (could be a whole semester’s course), then have a day or a week when they operate the store (with not so visible supervision.)