Murphy has an auto-sit, but I can still get a stand on command from him.
We sort of lured it. I held the treat in my closed hand in front of him. I'd move it back and he'd lift his butt up. Click for butt lifting. We worked up to it. Eventually, I wouldn't open my hand until he was fully standing. It was frustrating for him at first, which worked in my favor. He'd sit...wait...try a down...wait...cover his eyes...wait. Eventually, he'd get pissed and stand up, like he was going to walk away. I clicked the second he stood up, and he was right back with me.
Even if she sits back down before you feed the treat, you are still CLICKING when she is standing, which is the point. I'd also toss the treat out of her reach so that she HAS to stand up to get it:
If she's sitting before you can give her the treat, it would look like this:
She is sitting, upward movement toward a stand (through luring or shaping) or wait until she fully stand (depending on where you are with training)...Click, toss the treat, click when standing, treat, click when standing, treat. Keep clicking and treating as long as she stays up. Since you are just beginning to work on it, it doesn't matter so much that she is getting INTO the stand position. You want to reinforce that STANDING UP is what's getting her the treat. Eventually, you can get to the point where you are clicking for the actual act of standing.
If you want to "reset" her, I'd move to another position and see if she stays up. If she sits, just wait her out, then click-treat like crazy when she stands up...and keep going while she's up.