Broken up, inconsistent lip-line with no defined cupid's bow... fixable or not? (Photo)

I have a very 'broken' lip line, as in my lip line (particularly my "cupids bow") is not a consistent line that links up, it breaks up on my upper lip. I consistently have to wear lip liner to make it look fuller and like I have a cupids bow at all. How can I fix it? Can fillers fix it (I like my lips otherwise and don't want more volume) or will I need cosmetic tattooing?