Letrozole is commonly taken for several cycles in a row for ovulation, so wanting to repeat it isn't unusual. After an early miscarriage though, many doctors have you wait for one normal cycle before restarting it. Some also check why the miscarriage happened first.
Next Steps
Ask your fertility specialist whether this cycle is right for restarting letrozole. It depends on your bleeding pattern and test results, not a fixed rule. At 39, timing matters, so raise this clearly at your next visit.
Health Tips
Please check with your doctor before taking the next dose on your own, especially this soon after a miscarriage.