maybe take away the pull ups and use waterproof mattress covers? She'll probably realize she's doing it if she gets soaked.
My 2 and 3 year olds still wet the bed occasionally, but I just change the sheets and mattress cover. for the 2 year old who has more accidents, i also use the old crib mattress pad... so she has two layers... if it stays contained on the crib mattress pad, I just pull that and the sheet up instead of having to change everything.
On that new show "the Doctors" on CBS, Dr Sears said that most kids outgrow it by age 6.
Hope this helps!