Well, doubled is a little bit overrated. From the deepest point to todays value the price increased about 60%. There is some more space to reach the double value
But you are right, the price did make a big jump.
NXT has nearly doubled in value the last 2 weeks. coming from 3000 satoshi to nearly 6000 ! Prices aren't even at half the previous peaks .. Much more room to grow. Interesting to see how it will develop.