* Pre- (meaning before) - Preconclude: This is not a standard word, but you could use it to mean "to conclude beforehand" or "to anticipate a conclusion."
* Fore- (meaning before) - Foreclose: This means to prevent something from happening or to close off a possibility. It is related to the idea of reaching a conclusion and shutting down other options.
* In- (meaning into or within) - Incorporate: This means to include or to make something part of something else. It can relate to the process of concluding a decision or argument and integrating it into a larger context.
* Pro- (meaning before or forward) - Proceed: This means to continue forward, which could be seen as a way of "concluding" one step and moving on to the next.
The best way to understand what prefix to use would depend on the specific context and the meaning you're trying to convey.