Adding juice to already fermenting wine?

Thank you all in advance for any advice you can give...     My question/ situation is, I just couldn't help myself and I sipped away about half of my apple juice wine/cider during it's fermenting 🙃🙂...  
 It's still doing its thing & getting stronger and stronger (alcohol), so my question is, can I just add another gallon of apple juice and wait for it to be accually done?    (Patience)..    
 Im wondering if I should just start a new batch, or maybe, can I just keep adding to the original batch indefinitely?   - sort of like a bread starter that some people have had for years...
 I hope all of this makes sense!

Hi Joshua, welcome to Permies!

Yes, this can be done! One risk to be aware of when doing this is the possibility of introducing airborne wild yeasts or bacteria that may result in funky flavors, souring, or turning it into vinegar. All of these microbes need time, some more than others, to make a noticeable impact on flavors or aromas and if fresh wines are consumed promptly, things may never get a chance to be noticeable. Hope this helps!