6 months ago my daughter fell at school and dislocated her elbow.the doctor said it was better but it still hurts her all the time, should she go back?

Yes: Elbow dislocation/relocation is a simple process and unless the elbow is out of place for a day or so pain should be gone quickly.If maneuvered back into place within an hour or two the often don't complain after it's reset. 6 weeks is far too long for pain & xrays may be indicated.

Yes: 6 months is sufficient time for a child her age to heal from a broken bone or from soft tissue injuries around the elbow like a dislocation. If she is still experiencing pain at 6 months, she should be re-examined and have repeat xrays performed and compared to her original ones. See the orthopod who treated her before or one that specializes in pediatric orthopaedics or elbows.