Yes, you can re-take AS and A2 exams in the summer of 2016.
But unfortunately for those who sat AS in 2015 and will sit A2 in 2016, if you plan to re-take A2 modules for example during your gap year- this will not be possible any more. The grades you get in A2 will be final as those subjects will no longer be modular any more. People would have to take the whole subject again in one year or something sadly. Yet again, you may if your subject does not change until 2016/2017.