Should I retake the general GRE or focus on subject test? I took the general GRE two years ago and received V167/Q161/W5.0 or V98%/Q78%/W93%.

I am applying for PhD programs in applied mathematics this fall and plan on taking the GRE mathematics subject test.

My question is, should I focus on doing well on the subject test or also study and retake the general exam? 

If my general exam scores are "good enough" then I suppose I would like to simply focus on the subject test. On the other hand, I am slightly worried about my 78th percentile score in quantitative reasoning.
Other commentators have suggested that little notice is taken of GRE in graduate admissions, but I am a bit more reticent about this.  I think some faculty will give little weight to it, but others will use it as an estimation of your abilities (in conjunction with other evidence such as your undergraduate grades)  In any case, if you are going to submit these results as evidence of your abilities, you should make sure they put you above other applicants, instead of below them.

With that in mind, you are right to worry about your quant score - it is a bad score (relative to the program you are applying for).  The distributions of GRE general scores by intended major can be found here, and as you can see, for students intending to pursue "Applied Mathematics", the average GRE Quantitative score is 164 (SD 6).  Your score puts you above 78% of general test-takers, but it puts you in the bottom half of those applying for postgraduate maths.  Students who make it into postgraduate maths generally have very high levels of quantitative ability.  Around 20% of them get a perfect quant score in this test.

Based on this, I would suggest you retake the general test and try to at least beat the average Quantitative level for postgraduate maths applicants (GRE Quant 164+).  Your verbal and written work is well above the mean, so just try to hold your scores here, but really, you need to improve your Quantitative score.