I believe for every region except 8, the petition score is a 35 (one point higher than qualifying). For R8, it is a 36 (qualifying is 35 for L10 and 35.5 for L9) . This would have to have been scored at a meet this season. You cannot use last year's regional competition because it was a different level. If she made it to L10 regionals last year, then you could have used that. But I think the petitioning score enters in for that as well.
Also, the Dr note has to read that she will be cleared before the date of the regional competition. As for chances of approval, that depends on your region and likely how your DD did this season.