What do I say when a girl asks what would you do if I was there right now?

In cases such as these, it is usually a good idea to speak freely. In other Words, you can answer the question as asked. What would you do? There would seem to be a number of possibilities. You might want to:

have a long conversation and talk about everything that has happened while she was away,

give her a kiss,

go out for Pizza,

play a game of Scrabble,

etc.