Nuk bottles

My son (3 in January) still uses this bottle for comfort and his milk. I know he’s too old for it but he will not take milk from anything else. It’s a silicon nipple. I tried sippy cups, straw cups, and putting Winnie the Pooh stickers on more age appropriate cups but no luck.

Is there replacement tops so he can still use the cup but different top? I couldn’t find it on Amazon

*** confusion on my post I think. Post was for the cup. Not about milk or eating. Rather milk than juices. He has water too and doesn’t care what cup it’s in but will not have milk in those. But his milk bottle of the day is this bottle only