Responsible pastoral practice in these cases requires a more intimate knowledge of the specific persons and circumstances involved. To say more than this, including the habitual assumption of repentance right before a suicide when there is no evidence of it, is presumption or, at best, fruitless speculation. Your question is an over-generalization which implies that pastors would deal with all cases in an identical way. A pastor would have to deal with each case on the basis of the information which he had. The general principles which he would have to weigh would include the following.
Suicide is a sin.
Not every sin destroys faith. Suicide may well be an expression of unbelief and despair as it was in the cases of Judas and Saul. In other cases suicide might be a result of a sin of weakness or mental disorder. Whether faith still existed in certain cases is a judgment we must leave to God. The most the pastor can do is to point to evidence that faith existed in the heart of the person.