Cruz is young enough that he still has time to get some facial plastic surgery to lessen his "creep" factor (nose shadow over upper lip and droopy eyes). Then he should work with some Hollywood types to make his facial expressions, body language, and diction friendlier. Finally, he should work with a better comedian regarding his timing and delivery of his not-very-funny nerd jokes.
Guess 2016 just isn't his year.
Speech therapy would also help. A video surfaced some weeks ago of Cruz speaking ~seven years ago. A hardcore Cruz supporter noted how much easier and more pleasant he was to listen to back then. In the interim, he’s slowed his speech to an Al Gore rhythm and cadence, and a stronger Mr Haney/televangelist inflection has emerged.