Nikkei rises to 4-1/2 week high on weak yen, reform hopes

* Reform hopes on Shiozaki helps stock market sentiment - traders * Strong department store sales supports retail stocks By Ayai Tomisawa TOKYO, Sept 2 (Reuters) - Japan's Nikkei share average rose to a 4-1/2-week high on Tuesday morning as the yen slipped to a seven-month low against the dollar, sending exporters higher on hopes of a boost to earnings. The Nikkei gained 1.1 percent to 15,639.72 in mid-morning trade, the highest level since July 31. A planned cabinet reshuff