Have a Bachelor in one major thinking about getting a Masters in another degree

So I obtained a bachelors in one degree a while back and went into the Masters Program in the same degree but didn't really flourish so I stopped taking graduate classes.Now I work for an organization that gives their employees educational rewards after a year of service. I have thoughts about obtaining a masters in another degree.Now I was thinking in the major that I am switching to...is it a good idea to take the graduate courses and dismiss the undergraduate courses? The reason why I ask this is because some courses in the undergraduate level might be beneficial for the career I am trying to pursue.Could I just take those undergraduate classes outside of the graduate level just for the heck of it? I plan on speaking with an adviser at the University but wanted to hear from someone on here as well :D