9 month old refusing bottle

My 9 month old has been refusing bottles for 2+ weeks now and will only nurse. Since he was a newborn I've given him the odd bottle (medela calma) and he's never had a problem switching back and forth. However, for the last few weeks he doesn't get excited when he sees it and pushes it away if we try and feed it to him. Any tips or tricks to help him get comfortable with a bottle again?