I say go for it! I love the name Livia and plan on using it as a middle name for a girl when I have one. That being said, I did consider Liviana for awhile, because I love names that end in -iana! I love frilly, feminine, and--yes--"over-the-top" girl names. Hey, they're so beautiful, if you're not gonna be brave enough to use them, I will! (I actually kind of thought I made up Liviana at first, but I have seen it around here and there.) I think it's beautiful and unique. If you like it, you should use it.
I like frilly names, so I have to say I like this one. I just feel like she will constantly be telling people, "no, not Liliana, Liviana--"
I love Liviana!! I can't remember how I came across it, but I discovered it last year and thought it was a great name. However, it does slightly strike me as a trendy made-up looking name. But I think it's very pretty.