Goods in your market doesn't reduce the replenishment rate, Serp. That's a common misconception.

Instead, existing goods in your PM decays at 1.5% per turn, so it APPEARS as though replenishment is reduced.

Note that full replenishment is only added, AFTER all decay has been deducted for the amount of turns since you last logged in. That is, if you logged out for N turns, then

Units at login = (Units at logout)*(0.985^N) + (PM regen)*N