On some of the tasks, it is possible to go back and make corrections, but if the time limit has expired by then, it won't count anyway. Based on your description, I would imagine that is why she didn't include those correct responses in the scoring. I often include a clinical interpretation that estimates (qualitatively--no numbers) where his performance would have fallen if the task were untimed (and hence every correct response could be included).
There are not really rigorous research-based exercises to improve functional working memory or processing speed (although there are pricey packages that claim to do so, especially for working memory). If ADHD is the basis of the low scores in those areas, though, it may be that treatment or coping strategies for ADHD may moderate their effects in real life.
