I took the SAT once in March and got a 1540 (750 R&W 790 M) and a 15 on the essay (4/5/6).
(I took AP English Lang and got a 5 on the AP)
I’m applying to Rice, UT Austin, UC Berkeley, and A&M
Should I retake the SAT to improve my essay score?
No. Your application essays can overcome the SAT essay score.
Rice does not require or use the SAT essay component according to the latest Common Data Set. https://oir.rice.edu/sites/g/files/bxs1496/f/2017-18%202.%20CDS_2017-2018_WEBSITE.pdf