Answer

I actually have two. I don't agree with them, and I'm sorry they chose wrongly, but I completely respect their choice and accept them as they are. Usually, pressuring a child to come back leads to an even worse result both in terms of becoming more distant from religion and in terms of personal estrangement, so I don't recommend it except in very unusual cases where you actually have a chance. Usually, after the decision stage, it's already hopeless, and it's not right to keep going with it. By the way, in my assessment, in most cases this pressure is applied more for your own sake and less for the child's sake, and in quite a few cases to compensate for your own feeling of failure and for how you are perceived by your surroundings.
As a rule, if the child chose a different path, in my eyes that is a kind of success, as opposed to a child who remains on what I see as the right path out of inertia because it's their comfort zone. If they just drifted there and it wasn't a deliberate decision, then that really isn't a success, but you can't always know whether it's this or that; in most cases it's a combination.
If you're worried about the World to Come and her eternal fate, in my opinion we can trust that the Holy One, blessed be He, does not make unreasonable demands of His creatures. If a person is not wicked and isn't doing this casually, but truly thinks this way, or at least it seems reasonable to them, then they are under compulsion and are not punished, and certainly they are not lost and will have repair in one way or another.
As for your public image, that's a common consideration, but it's really not legitimate. The child is not supposed to act in order to protect your image, and you are not responsible for their decisions. If you accept things and respect them, and don't try to hide it or evade your surroundings, because every person makes their own decisions and you are not responsible for them, you will feel more whole and less pressured, and you'll be able to act more properly.
To sum up, I very strongly recommend, both tactically and substantively, respecting your child in whatever path they choose. They are a different person, and they are the one who has to make decisions about their own path. It's hard to get used to it, and of course you don't agree with their path, but that is the situation. Good luck.