Without stepping to an X2 (SI's fat batt)? That would greatly increase your battery life.
Clearos have a tad more capacity, but they look a little odd on the regular Volts, and can make it hard to push the button on manuals (at least for me). There's talk of higher capacity (longer) Nanos though, that SI might be working on. There are XL cartos too. I think those hold a tad more liquid - and you can look into inserting them into a
tank...or you could wait for the T3s, which would probably still work with the regular batts - but the regular batts probably wouldn't stay charged long enough to
vape through all that liquid.