Offer smaller amounts of milk more frequently. Offer the bottle in a new environment or cozy environment. If you already offer your baby solids, give it to him along with his milk. He can either drink milk with his meal or drink it before the meal. That way, he can associate different tastes with the experience of drinking from a bottle. What once worked for your baby in the early months may not interest him anymore. For instance, a slow flow nipple could make it more difficult for him to suck. Or perhaps you’ll have more luck with the brown nipples instead of the clear. You can also offer milk in a sippy cup. Just throwing in some ideas that may work. Best of luck!