Buskers,
Night time dryness is not within a child's conscious control UNLESS she is waking up but choosing to wet her bed rather than get out and go to the toilet (this is possible if e.g. she has become scared of the dark, monsters under the bed etc).
If you can exclude the latter possibility (does she get out of bed to go to the toilet on other night perfectly OK? Does she talk about the dark or about monsters? Does she have a decent night light and is the route to the toilet well-lit? Might she prefer a potty next to her bed for a few nights?) then there is no way that threatening her with nappies will help.
An awake child can choose to go to the toilet, so wetting themselves is at least to a degree a conscious choice. An asleep one cannot, so 'punishment' for a wet bed cannot work - and is probably counterproductive as we all know how being nervous makes us MORE likely to need the toilet.
Keep an eye on fluid intake overall (don't limit it, but see if she has been drinking more than normal). Does her wee smell at all, as it could be a minor urinary tract infection? Is she absolutely well in herself - DD, my non-bedwetter, used to wet every time she was brewing a cold but at no other times? Has there been a change in her life e.g. holiday, about to start new nursery etc - as i said above, nerves affect bladders. Has she recently had a massiv growth spurt?
DS was dry in the day at 2.5. And dry at night round about his 9th birthday - the two are not connected, because one is a conscious and one an unconscious process. I changed beds several nights a week for most of those intervening years, because his issue was a lack of a hormone, so he produced as much urine during the night as during the day, which is enough to soak through any nappy / night pants available in 10+ hours asleep.
This is a short-term phase for your DD. Getting cross is wholly counterproductive. Investigate possible causes calmly, do not threaten or punish, and it will almost certainly pass. If it doesn't, it's worth a quick trip to the dr to rule out an infection, then you and your dd together can decide whether she would prefer to use nappies for a short while to help her to sleep better 'until her insides grow up a bit more'.