Lexi is such a cute name... but i think too close to your niece's name!
Sharni is different & pretty! (I don't know what a "sarnie" is, so i don't get the joke! lol)
Isla i'm not too fond of, personally.
And Amelie is nice!
I would definately say to keep looking until you find a name you love... and maybe in the meantime you will come to love one of the names already on your list!
How about names that are similar to the ones on your list?
Lacey, Leah, Shiloh, Shyanne, Shelby, Isabella, Ivy, Amelia, Amber, Emily