An indication may exist but be too weak to identify the subject with confidence. In that case explicit mention serves caution against unreliable inference (ضعف التعويل على القرينة).
أو الاحتياط لضعف التعويل على القرينة
Or as a precaution because the contextual indication cannot safely be relied upon.
If one says «زَيْدٌ لَقِيَ عَمْرًا فِي السُّوقِ»—“Zayd met ʿAmr in the market”—and then adds «مَرِيضٌ», the audience may not know which man is ill. «زَيْدٌ مَرِيضٌ» or «عَمْرٌو مَرِيضٌ» would resolve the uncertainty.
The subject's reappearance is therefore not gratuitous repetition; it removes competing referents and safeguards understanding.