I love nova as a nickname but I was wondering what names can you use it as a nn for?
Novaleigh! I love the name Novaleigh! (Or Novalee).
Hmm. Nothing automatically springs to mind, except for Casanova. Haha.
There’s Novalee or something like [name_f]Nora[/name_f] [name_u]Avery[/name_u] could give you [name_f]Nova[/name_f] by taking letters from the beginning of both names. It’s a little bit of a stretch, but could work if you really want the nickname [name_f]Nova[/name_f] without just using [name_f]Nova[/name_f].
[name_f]Nova[/name_f] works on its own and isn’t typically viewed as a nickname in my experience. It is also a modern name, which makes it less inclined to have longer variations to associate with it. Since it means “new” and is also, basically, another word for star it could potentially be a pet name, as in unrelated to the name the way we might call a kid Chief or [name_m]Ace[/name_m] or [name_f]Sunshine[/name_f]. 
A little contrived but you could name her after a constellation and related Super novae: These are BIG names for a kid: [name_f]Andromeda[/name_f], [name_f]Ursa[/name_f] ([name_f]Ursula[/name_f]?), [name_f]Cassiopeia[/name_f], etc. and nickname her [name_f]Nova[/name_f]?
The only name I can think about is [name_u]November[/name_u], assuming you’re open to use word/month names. I prefer [name_f]Nova[/name_f] as a stand alone name though.
[name_f]Novella[/name_f]
[name_f]Novalie[/name_f]
[name_u]November[/name_u]
[name_f]Novelia[/name_f]
[name_f]Nolwen[/name_f]
[name_u]Nouvel[/name_u]
Thanks for the feedback! I like novaleigh and using constellation names is a great idea!
Novalee ? [name_f]Genoveva[/name_f] ?