life with a grade schooler: iPad time limit

Dear Apple,
You need to work on improvements of your time limit function on iPad.
My 9-yr old outsmarted/hacked your current program. She learned that if she closes her iPad once the time limit-reminder pops up and then wait for a few minutes, the timer resets.
And that is why she could have longer time with her programming/minecraft while at the same time follow the rules imposed.
Please make the improvement ASAP.
Yours truly,
Out of sorts (proud or frustrated, can’t decide) Mom