Notice what she actually enjoys
A surprise dinner is only thoughtful if she enjoys surprises and can make the time. Use these questions to learn the details: quiet or lively, planned or spontaneous, a gift or uninterrupted company. Tell her your preferences as well so the conversation goes both ways.
Follow up on one answer
Choose something you can do without making a grand promise. If she misses a place you used to visit, suggest a day to return. If a memory matters to both of you, describe it in a note using your own words. Avoid turning the list into a competition over who knows the relationship best.