He gave it a shot, it failed, time to move on to new strategy, not to repeat the same over and over again.
A strategy can be called "failed" if it was implemented completely, a ceasefire is not worth the paper its written on if the govt acts opposite of whats on the paper (Hint: no 'chowkis' in FATAs on paper but next day there were several police/LEA chowkis). Paying few million bucks to Mehsud one day and then putting blame for all terrorism/attempted-murder on Mehsud tells a lot too.