He sent me this what do I respond?

Okay so I met this guy in uni during our lab session and I've only met him 5 times this year and all were during the class.

He seemed interested so we flirted several times and started a streak on snapchat. But people flirt all the time I never think much about it.

We're on a summer break (we're in australia) and wont see each other again until next year. So I told him today not to expect much from me and just to see how it goes next year when we can properly go on a date. And he said this to me. What do I say back to him? We're both 19