I had the same thought. I tried not to heat it up too much to keep the carbonation. By gently warming it up, some stayed.
What I thought is that if I have some leftover dark beer (most are in 500ml bottles and it's too much for me in this season), I can make it revive by using for hot beer 😁 I'll try this.
That is interesting, I will definitely try it! We have some nice dark beers which I will definitely try with some spices I have on hand. Thanks so much for the idea!