My DS (now 11) learned his times tables years before the timed tests his school gives in 3rd grade. To refresh his skills and speed him up, we started skip counting (counting by 2, 3, 4, etc. to 12 X the number) on the way to school.... always helps to have a captive audience :-)
Not only did it help him but his brother who was 5 at the time learned as well, much to the dismay of his kindergarten teacher... ugg! It certainly isn't exciting to refresh knowledge you already (boring! beneath me in my DS' opinion) but the skip counting as fast as we could was sort of fun.
Also, 'Math Drills' or 'MathBoard' for the iPad are good practice and more exciting than paper.
