That would depend on what the reward toy is. If it's a squeaker, then I'd get a couple of squeakers, keep them around at all times. Suddenly burst into a game.
A flirt pole is a great way to build drive and impulse control. You can make your own using her favorite type of toy.
Remember that if you really think about it, the toy isn't what is as important to the dog, it is your interaction with her. Some dogs love to fetch - although some types of toys really turns them on, it's the game they like. Some dogs love to carry a toy with them, but get really turned on when the handler engages in the game.
I've got a dog who loves to fetch. If I add a squeaker to the mix he goes nuts. So I know a squeaker (ball or stuffie doesn't matter) is added to the mix, he is over the top. But if I stop playing the game, he'll entertain himself, but at a much lower level (lay and tear up the toy).
Hondo Von Dopplet L Bauernhof "Hondo"- GSD
Lilie's Tug McGraw "Tug" - Golden Retriever
Maggie - Mini Dachshund (Rescue)
Lonestar Pivo - Texas Blue Lacy
Ashe - Barn Cat
Katie / APHA