People have given you lots of good ideas. It is really good that your daughter is keen to continue. A couple more things ...
She must have had an accompanist in the exam - what did s/he say about how it went. Or was it her teacher that accompanied her ?
Did your daughter have any practice sessions with the accompanist before hand ? These tend to be very useful for finding out how ready someone is to take the exam, and for helping a child get their intonation right. They are also just a good way to get a second opinion.
Also, did she listen to the pieces on the ABRSM cd that comes with the music so she knew how they should sound ? It is well worth doing.
Other people have mentioned things like video'ing herself so that she can see how she sounds.
It is well worth looking at the syllabus and seeing what needs to be covered, and checking that the teacher is covering everything. In our case a little chat with the teacher made it clear that he didn't feel he had much time to cover aural, so we found someone else to do a few sessions with our daughter (as it happened the same person that was going to accompany her in the exam). Over something like three sessions she went from potentially getting zero, to possibly getting nearly full marks.
For sight reading, read anything. In the early days my children sight read from nursery rhyme books, and later from easy play pop song book (I still shrink at the thought of the easy-play Abba book with a play-along CD) as well as more formal things. Just sight read something, anything, every day.
It is also worth doing a couple of practice exams before hand, just so the pupil can see what it feels like to play all the pieces through one after another with a pianist, and then be asked for random scales, and then do the other tests. Mini-concerts for relations are also a good idea.
Exams are a mixed blessing - when the results are good they can be very confidence inspiring. When the results are bad they can destroy the confidence. It is well worth spending a little time ahead trying to maximise the marks.
I am afraid I would change teacher. Do you know his other pupils ? How do they do ?
Where are you based ? Perhaps look for a teacher that has a program of group lessons.
Lastly, holiday courses are a very good way of meeting other children who play, and of meeting other teachers and seeing how other teachers work.