I would recommend a retake, if you want a T20. Not all URMness is treated the same (African-Americans > Latinos and American Indians), and even within given groups, there are differences, e.g., Mexicans and Puerto Ricans tend to get preference over Cubans. While everyone knows "someone" who got into a T14 with a 150ish, for Latinos and Indians, the chances are slim, unless you have significant soft factors and a very high GPA. Make sure you get LoRs which attest to your academic strengths, and apply very early (Sept-October.)
If you're okay with a lower ranked T1 or T2, then you might not have to retake, but the competitiveness for those spots will increase, particularly in the West and Southwest, where there are large Latino populations. Once again, get your application in early.
ETA: Case and point: While I was typing this out, Cosmo provided her experience --> soft factors and wicked high GPA.