NEW ALBANY — Commercial Vehicle Group is going to continue operating in Monona, Iowa, reversing a previously announced plan to close the plant and shift the work to Mexico.   Commercial Vehicle, which is based in New Albany, said it made the decision because of high product orders and a tight labor market in Mexico.   The Monona plant makes wiring systems for vehicles. Commercial Vehicle's announcement is not a surprise. The company had previously said it was re-evaluating the decision to close the plant.