How do I patch NWN2?
Solution 1:
To the Vault!
The Neverwinter Vault may be useful to you; specifically their patches section.
Change the game drop-down to 'NwN2' and patch drop-down to 'Obsidian' (or 'All') and it should bring up all the files you require to update the game from vanilla to a version that satisfies. I believe you need to run each file (i.e from 1.00788 to 1.02809, etc.) individually as you require to update the game.
Alternatively, there is also an additional, optional NwN2 Patcher by tnt220 which would let you update the game offline, but requires the patch files (linked above) to be obtained prior to using the tool. This appears to be an automated process which could reduce some of the monotony of running each patch individually.