I would also say that SAT scores are a fairly good predictor of GRE scores if you plan to go on--mine were almost the same (percentile)
If you have the option of taking the MAT (which I did), it's a lot easier....and scoring high can be easier as well...of course I was an English major and had French and Latin which helped tremendously...
Test prep books can be incredibly helpful in terms of improving standardized test scores. I particularly liked the Princeton Review book, but I used three in all. I think that retaking the SAT would be a good idea, if for no other reason than that she will likely be taking the GRE or a similar exam one day. Test-taking is a skill that can be learned.