At the time appointed for showing cause, or at any time to which the hearing is postponed, personal service of the citations having been made upon the persons named therein, and the required publication, posting and service of the notices having been made, and all duly proved, the court must proceed to try the issues joined in the same manner as in an original contest of a will. If upon hearing the proofs of the parties the court shall decide that the will is, for any of the reasons alleged, invalid, or that it is not proved to be the last will of the testator, the probate must be annulled and revoked; and if the court shall decide that the new will is valid, it may admit the same to probate in the same manner as originally upon the probate of a contested will.