I believe the problem here is much deeper and you need to carefully consider the reasons for the rejection before thinking about an appeal. Usually, an appeal is to challenge the legal reasons for rejection, not to fix an application, and not just to give it another try.
Much of the details needed to comment on this particular case are missing but from what you have written:
justification for the purpose and conditions of the intended stay not provided,
and means of subsistence not provided,
It appears the visa officer has serious doubts about your real intentions and plan to visit Spain, and your financial resources for the trip. Most developed countries assume by default that you're an illegal immigrant and the onus to prove otherwise (i.e., you are there for a legitimate reason, you have the financial resources to easily cover the trip, and you have strong reasons to return to your country before the expiry of your visa) are on the applicant. Some countries like the US state this explicitly but almost all countries consider this.
You mention that you need a new NOC so I take it you're either a govt. employee or that of a bank or semi-govt. organization. If you were going on official business or an event, giving a new itinerary makes no sense and does not justify the reason since it will have already passed. So your appeal won't be justified. If this was for tourism, then your best bet is to re-apply after some time but only if you can strongly justify your application, e.g., a strong travel history, strong and legitimate financial and professional ties to Pakistan, and a solid and justifiable travel plan.
While you can consult a travel agent or lawyer for advice after seeing the particulars of your application and rejection letter, an appeal doesn't look justifiable from what you have shared.