My dogs are important to me

I have three dogs and I celebrate their birthdays and Christmas with them. I go all out though and have to sell their toys every few months. Which I always go through and decide what they don’t like. The issue is, my dachshund loves balls which means she has a million but uses them. Her birthday is coming up in May and idk what to get her because she already has so many balls and I don’t like giving them much food on celebrations. This is because my dogs have struggled with weight so I try to be careful. My dachshund loves opening gifts and I just don’t know what to do besides buy more balls. They don’t make enough toys for dogs.