If your child is active in the morning and is not at all drowsy, then she is getting enough sleep.
But the general ways that will help to increase night sleep are
1) increase activity in the morning - try sports or physical playing
2) reduce water 2-3 hours before sleep
3) avoid naps during the day
Next Steps
if that doesn't help - can try melatonin (noctura) as the other doctor has already adviced, it's one of the safest medication for inducing natural sleep.
Health Tips
if not able to sleep at all, morning drowsiness is present, better to consult a doctor in person again