Largely speaking, the applications can be reconsidered, so there could be a reapplication. You could apply for reconsideration, or you could challenge in Federal Court.
As somebody who practised law before I got into politics, that's not an option for many people. The reality of the situation is that the decision-making process on independent case files has to remain independent from me, but the process to reapply remains available, in most circumstances, to people who are seeking to come to Canada.