Hello & welcome Graeme Twist
You wont get much better battery life out of any cigalike e-cig I'm afraid
You would do so much better to upgrade to an ego style/sized battery.
I agree with the above. How can you expect to get any more battery life from such a small battery. Size restriction affects the battery life. I seriously doubt you'l find anything which lasts much longer than you currently have at that size.
At some point, IF YOU ARE TRULY SERIOUS ABOUT QUITTING CIGARETTES, you'll make the concessions to elimimate your priority of size/shape for the better performance/battery time on an Ego or a mod.
I also started out with the cigarette size batteries, and they got me to stop smoking. However, I was convinced after 3 weeks that they wouldn't KEEP me off of cigarettes because of poor battery life and the limitation of juice attachments/flavors available.
I decided to skip the intermediate eGo batteries and got a mod that used replaceable rechargeable batteries which would easily last me the entire day on just one battery. I used tanks with had a larger capacity so I only needed to fill them once every couple of days. So I gave up the small form factor of cigalikes for the better performance, better flavor, better vapor, longer battery use, larger tank capacity, and CONVENIENCE of using a mod.