The list of officials who are leaving the executive branch in the wake of President Reagan's reelection continued to grow yesterday.

J. Erich Evered, chief of the Energy Information Administration, has resigned, effective immediately, Energy Department officials disclosed. At the Office of Management and Budget, Donald E. Sowle, administrator of the Office of Federal Procurement Policy, said he would retire by the end of the year.

At the Housing and Urban Development Department, general counsel John J. Knapp announced that he would leave "right after the inauguration" to enter private law practice in Washington. "My plan always has been to stay through the first term and not beyond," he said.

Education Secretary T.H. Bell, the undersecretary of Housing and Urban Development, the assistant attorney general for legislative affairs, three assistant secretaries of the interior and three high-ranking Agriculture Department officials have already announced their resignations.

Defense Secretary Caspar W. Weinberger yesterday told Cable News Network, in an interview to be broadcast today, that he wants to stay in the job. Weinberger said he and Reagan "have not had any discussions" about his future.

During Evered's 3 1/2-year tenure, the Energy Information Administration budget was halved and the staff reduced by 40 percent, but he contended that the office was producing information that was more timely, more reliable and less partisan. At times, that posture rankled top department officials.

In a letter to Energy Secretary Donald P. Hodel, Evered said he was "deeply concerned about how this country will meet its needs for conventional oil and gas supplies over the next 25 years" and indicated that he would take an unspecified job involved in finding solutions to those problems. "What I want to do cannot be done at EIA," he wrote. Evered could not be reached and his staff refused to comment on what job he would take.

According to DOE officials, Evered will be replaced temporarily with Helmut A. Merklein, assistant secretary for international affairs and energy emergencies. Jan A. Mares, assistant secretary for policy, safety and environment, will replace Merklein. Robert C. Odle Jr., assistant secretary for congressional, intergovernmental and public affairs, will oversee a reorganization of Mares' office.