Since she is an adult, it'd be pretty rare for a hypo episode - so I'm glad you haven't seen one in a year now. That's great
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I agree w/ your vet...just leave her alone, increasing times as you go, gradually. There are different things that may be calming or helpful: pheromone plug-ins or collar, aromatherapy (balms you put on their ears/head or sprays etc), Rescue Remedy. There are even dog DVDs you can buy that play stuff that is supposed to be engaging and soothing to dogs...there is supposed to be one that is super good, but can't recall the name.
You can also rub a small bandana on yourself, and then tie it around her so your smell is close to her. Keep her in a smaller, secure area rather than allowing her to roam the house.
Also, what about a webcam so you can keep an eye on her...?