i don't think her lashes are rooted, but just glued on (but i could be wrong, i don't have her, i'm basing only of pictures)
if thats the case, you could remove the remaning lashes with some hot water to soften the glue, and reaply some fake lashes of your choice since you don't want the super full look
Ooh, you should definitely get one! They're the mostest!!
But just to increase your pony knowledge, they are in fact rooted! I own several (it's a bit of an army at this point, more like an invasion!!) and I own one who arrived with her eyelashes buzzed, and there are rooting holes on her eyeliner where the lashes have been rooted in!
You're going to want to reroot them, if you want to repair them in the way they were done before - however, there's nothing stopping you from slapping on a pair of falsies, either! There might be some really cute alternatives out there to try! There's also a lot of great tutorials in the Customs forum, here's a link to the pinned topic about various tutorials:
https://mlparena.com/index.php?topic=283445.0 But basically, I think if you want to restore her as she originally was, you'll want to root in some black nylon hair then trim it down to size, maybe after giving it a little curl!