I think i'd go further though and use diapers not pull ups. At age 4 (aside from any developmental delays) she should be aware and able to prevent the majority of accidents, especially if she has been trained for some time and is truly accident free at home. If it is just a behavioral thing then the impact of 'act like a baby, get treated like a baby' will be driven home faster with actual diapers.

I just caution such a route if there is any chance of it being more than just behavior. If it is due to an underlying condition then I'd be weary of shaming her in case it is a long term issue!