There are two answers to your query:
1. Should you take up your GRE Bio test? Yes. A good score in the subject test can always help you, and a bad score cannot harm you as you can simply chose not to forward the score to your selected universities. So, take up the Subject GRE test irrespective of your general GRE score.
2. Should you retake the general score? Again, depends on your last scores. f you have got more than 750 in QGRE and 500 in VGRE, then you might decide against retaking the test.