I have a Sweep Picking course that has a lot of arpeggios with a hammer on after the first note of the arpeggio and a pull off after the last note of the arpeggio.

For instance pulling off from the 17th fret to the 12th on the High E string.

It has greatly strengthened my technique. Having a good guitar/setup is important too. My last guitar made legato a nightmare but my current guitar makes legato much more of a breeze.