What can be done if your Visa application was denied.
Get your GCMS Notes which the visa officer made while examining your application. (Keep in mind that it is also possible that the new application will go through another visa officer who could have a different view of the documentation provided.)
You should also analyze your eligibility for an appeal, either with the Immigration Adjudication Division (IAD) or with the Federal Court of Canada. You will typically need a lawyer in Canada to get this done for you.
Correct Initial Errors
Reasons Your Canada Visitor Visa May Have Been Rejected:
You have misunderstood the test for issuing a visitor visa TRV
You have submitted only the documents on the IRCC checklist
You didn’t submit evidence of all your connections to your home country to prove you will return home
You didn’t submit affidavits to support your application
Your invitation letter was not detailed enough
It is advisable to submit as much proof as you can, beyond the minimum that the IRCC requires.