The reason that there is not accounting for the 'Bradley effect' is that it is highly questionable that it ever existed in the first place and its impact has diminished to the point of being statistical noise at this point. Nate has had several great articles on the site showing how the Bradley effect is BS.
The 'Bradley effect' is only one of any number of possible phenomena that may occur and distort the results. Perhaps a new phenomena will occur and it will be named the 'Obama effect'. In 2004 the exit polls showed that Bush had very likely lost but this was wrong. Only after the event did they they came up with a explanation.
