Well it sounds like your really heading in the right direction & don't need to do to much different. As with any sort of training, at the start you'll notice a LOT of improvement, then you might go a period where you don't seem to improve much, that's where you just have to keep pushing & you'll start to notice some improvement again... By the sounds of it your pushing yourself to the limits every time you train which is great & it will FORCE you're body to adjust & become more efficient & develop endurance. As somone said though, it could be a case of overtraining. It might pay to add an extra day off from training here or there, or even take a week or 2 break if you've been training the 8 months without stopping.. When you come back to it it'll give your body an initial shock again & force it to adjust itself....

A good technical way to improve endurace is to really look at your training & measure certain things, like running for a hour & your totally nearly ready to pass out, next time run for an hour & 5 minutes, then an hour and 10 minutes... I mean you could even just go up in minutes. A minute extra a day is an extra half hour in a month, and over 6 months it's well, you get the picture.....

That's the same way bodybuilding work up the weight. Tiny little improvements even over a long period still equal big gains. Just look back at how far you've come over the past 8 months? If you stick at it you'll look back at today in 8 months time & realise how far you've come since now...

One last thing, adjusting your diet may help you get that little bit further? Perhaps having a higher carb meal a few hours before your workout could sustain your energy a little longer? maybe you need to drink a little more water just before your workout??

Little things like that can make a big difference when you reach a limit that seems hard to break..

Anyway good luck with it all...