A 15-month-old girl from Delhi is brought to the immunisation clinic by her mother. The child's immunisation card shows: BCG at birth, DPT-1 and OPV-1 at 6 weeks, DPT-2 and OPV-2 at 10 weeks, and DPT-3 and OPV-3 at 14 weeks. The mother states she has been unable to bring the child for follow-up visits due to family circumstances. On examination, the child is healthy with no contraindications to vaccination. According to the current UIP schedule, what is the most appropriate next step in immunisation?