The fastest way to build up speed is to slow down. Get a metronome (or similar 'app' type of thing...), and play the licks, scales, runs etc at a comfortable speed. Every week, turn the metronome up 5 bpm, rinse and repeat. Do not try to play fast. Play at a regular speed, and increase it slowly. That's the fastest, and most sure-fire, way to build up speed.
Disclaimer : a medium-sized bucket of Patience is required; it helps a lot. Renew whenever it runs out (as I suspect it might ...).