
Half the current amount morning and evening.
As someone else said you can bulk out with cooked veg like green beans, also a logn lasting chew like a cows hoof (empty not filled), to give her something to do.
Just like us the only way to loose weight is to cut the food down quite a bit.
She is obviously eating well over maintenance to have put the weight on, so going down to half, and then increasing slightly once the weight is off is the only real way to go.
I have found with my own breed that easily gains and only eats half the recommended amounts on most food guidance that feeding less of a good food is better than giving more of a diet food with fillers. They keep in better body condition and coat.
Having had the weight battle with first dog, with the next 9 I have been careful to not allow more than a little to creep on.
It is amazing how my young entire most active girls eat nearly twice what the older spayed ones need to keep at same weight.