I think you have to learn to distinguish between a not so great date and someone who may be uninterested. I think if it's just a bad date - maybe you're both nervous and awkward - you have nothing to lose going on another date. For a lot of people, it takes time to build chemistry and interest.

On the other hand, if she seems generally uninterested, isn't really trying to get to know you, is on her phone the entire date, don't waste your time.

As far as energy and $ goes, maybe you should suggest dates for activities that you enjoy? Sometimes I drag my dates to happy hour at the climbing gym for example. Great place to break the touch barrier, teach her something new, refresh your skills, and get a workout in.