Not every meditation session will be the same, nor will you achieve the stage of the journey as before. Your experiences since the previous time, and your current state of mind will have a big affect on how well you stay seated in a mindless state.
You have the tools to walk the path, but you must hold steadfast onto one particular tool. Do not jump from one facet to another (One day focussing on nostrils, next on sights and next on audibles), each tool will need to evolve into a stronger tool with heightened awareness.
Spend a long time honing your awareness, do not even expect anything special. Even when you experience something, ignore it, just sit and watch/listen, do not analyse or even try to understand it. When you try to contexualise what you are experiecing, your mind goes haywire and everything unravels like a dream. Just do it with Love and appreciate Creation for what it is, Life.