Serious Bed-Wetting

No not me!lol
Help! Viona has a serious bed-wetting problem. Everynight night we wake up because of this! Before we sleep we see to it that she goes to the bathroom and pee but it still doesn't work. She consumes 3-4 bottles before she sleeps. We are worried that this might go on for a long time since she consumes more and more milk as she grows. There isn't any problem at day time coz she's already potty trained. She only wears diaper during night time.
What should I do?!