How can we appeal successfully after refusal? We have 2 refusals from the same French embassy. The only reason for refusal was, "Not sure the applicant will leave the country on time."
Basically, you should try to show you have strong ties with your country of residence, things that would compel you to come back and make an illegal stay in the Netherlands less attractive. A good situation/job, family, a house, etc. could all go some way toward that but at this stage it might not be enough. Consulates have a large “margin of appreciation”, especially for this reason.
In practice, you should submit any document that would establish that and could also write a letter articulating your arguments (your wish to come back to your country, etc.).