My ds has similar scores, and issues with basic math fact regurgitation, especially when timed. This may be somewhat a result of being 'beyond' 3+6. 2nd grade timed sheets on this were reaaaalllly frustrating. Now he's in 3rd, and we had him doing 'timezattack' on his own, he liked it, learned it and is doing great on all these worksheets. We also try to show how the comkutation part of math is just part of a larger very fun subject. So for him it has to be a combo of interest, not too much repetition, and self confidence. Math is again his favorite subject.