When new shares are issued to retire debt, the company saves on interest expense, so after-tax profit goes up (assuming economic conditions and operating profits stay the same). But this increase in profit is usually not enough to offset the increase in number of shares, so EPS gets diluted. And dividends are paid out of EPS, so they drop too.
However, the risk of the new lower EPS should also drop (less debt, less risk). Lower risk deserves higher P/E. How much higher? In practice it's not predictable, just like the share price.