Retake if 1500 falls below the middle 50% at schools you seriously want, if your colleges superscore so a second sitting can only help, or if a scholarship threshold sits just above your current score. If none of those apply, your time is better spent on essays and the rest of the application.
At 1500 the honest answer is usually no. The score is already at or above the middle 50% almost everywhere outside the most selective handful, and the marginal admissions value of another 20 points is small compared with what the same hours would do for essays. The exception worth taking seriously is a named scholarship threshold sitting just above you.
The full picture, with the surrounding detail, is in Is 1500 a Good SAT Score? In Range at Every College.