Staying dry at night time is something that cannot be 'taught'. They're either ready, or they're not. Is she keeping her nappy dry? Or at least not waking up with a soaking wet nappy?
A special connection between the brain & the bladder which basically releases a hormone to slow down the production of urine while asleep needs to form properly, or they need to be able to wake up from the feeling of needing to wee enough to get up & use the toilet.
Our 4 yr old still wears nappies at night. She's desperate not to wear them anymore, but when we've tried her with just undies, she gets really upset when she wakes up wet. So for us, it's not worth it yet.
If you wanted to give it a go though, maybe try taking her to the toilet before you go to bed while she's still asleep to help her get through abit longer. Have her go to the toilet before she goes to bed, and it can help to make the last drink about an hour before bedtime. If she does start mucking around in the bathroom in the middle of the night, simply put her back into bed if you wake up. If you're worried about her tripping or playing in the bath, clear a decent path for her so she has nothing to trip on, turn the bath taps off TIGHT so its not easy for her to turn them on, and just incase, KEEP ALL PLUGS WELL OUT OF REACH!!
Good luck smile