We will be spending 5 nights in Paris prior to our Loire Valley to the South of France tour. My daughter is vegetarian and I'm having a hard time finding restaurants that have good options for all of us. I'm looking for a couple of options in Saint Germain/Latin Quarter/Isle Saint Louis, one in Montmartre, and a Seine Dinner Cruise. Price wise, I'd like to be under €50 per person (drinks excluded), but will spend more if it's worth it. I'm sure places like L'Arpege are amazing, but I really can't justify spending that much on one meal.
My wife and I are both vegetarian. We have had minimal issues in Paris and most of France. We find most restaurants accommodating and definitely didn't need to spend 50 Euro per person without wine. Now, if you daughter is vegan.....you might have more challenges.
A great website to help find suitable restaurants:
https://www.happycow.net
This recent thread might help: https://community.ricksteves.com/travel-forum/france-reviews/vegetarian-in-paris-a76ff6a5-d175-4a15-81de-33ae1bab9f71