When to stop applying and venture to other options for summer

So, time has passed and the jobs i interviewed for are taking quite some time to get back to me. At this point cold-calling and various channels are close to exhausted and I am still without an internship for the summer. I am a rising senior. What should I do.. and when should I call it quits and just start prepping all out for full-time. (I am looking to do full-time IB)