Yes — NISM exams can be retaken; candidates can re-register and reattempt the exam after a failed attempt, subject to NISM’s standard registration process and fee.
There’s no limit on the number of attempts, so a failed exam isn’t a dead end — it typically means revisiting the specific weak topics and re-registering for the next available slot. Structured preparation the second time, rather than re-reading broadly, tends to work better.