The Reagan administration, which is expected to conduct its second underground nuclear weapons test of the year early next week, is asking Congress to fund a $1.9 billion effort to upgrade the Nevada testing and research complex, according to data sent to Congress.

The multiyear "revitalization" program is designed to improve the Nevada facilities so they can continue to "maintain and improve current weapons and develop new weapons for the nuclear weapons stockpile in accordance with national security requirements," according to the Department of Energy budget for fiscal 1987.

The U.S. test, which could trigger an end to Soviet leader Mikhail Gorbachev's eight-month self-imposed testing moratorium, is expected to take place Tuesday, informed sources said. Gorbachev has said that the first U.S. test after March 31 will bring a halt to his moratorium.

Under current plans, Tuesday is also when Soviet Ambassador Anatoliy Dobrynin is scheduled to pay a call on President Reagan, according to administration sources. U.S. officials are hoping that the Soviet envoy, who is scheduled to return here from Moscow tonight, is bringing the long-awaited word from Gorbachev on the timing of his next summit meeting with Reagan.

Gorbachev has not officially responded to Reagan's invitation, delivered in early December, a few weeks after their Geneva summit, that the next meeting take place in Washington in late June. The Soviet leader has publicly tied the setting of a summit date to signs of progress in arms control.

He has also repeatedly called on Reagan to join his nuclear testing moratorium and has spoken of such testing as an area in which progress in negotiations would justify an early summit.

In an interview released in Moscow Wednesday, Gorbachev criticized the state of U.S.-Soviet relations, saying: "We have discovered . . . that as soon as we make a step forward to meet the U.S. position, the U.S. takes a step back from it."

He also asked Washington to reconsider his proposal for a meeting with Reagan in Europe to discuss an end to nuclear weapons tests.

For his part, Reagan has invited Gorbachev to send scientists to a nuclear test in Nevada later this month to observe a new monitoring system that records the size of the explosion.

Although the Department of Energy has refused to provide details on either the timing or the purpose of the test, some sources on Capitol Hill said it could be a so-called "weapons effects" test. In these multipurpose experiments, supervised by the Defense Nuclear Agency, the military services expose weapons and other equipment to a nuclear blast to see its effects.

In this test, according to testimony given Congress last year, new warheads designed for the MX intercontinental missile and the Trident II submarine-launched missile will be among the items exposed to radiation to test their durability. According to Pentagon sources, the purpose is to see whether the items could survive radiation given off by the interceptors in the new Soviet antiballistic missile system being deployed around Moscow.

A major project in DOE's construction program, scheduled to begin this month, is a $70 million multistructure facility at the Nevada site that, when completed in 1990, will replace two nuclear device assembly areas that the department has declared unsafe.

Within a 22-acre "high-security exclusion area," DOE will construct buildings with 18-inch-thick cement walls within which the nuclear test devices will be assembled. Each area that holds special nuclear material will be equipped with interior security alarms and video "assessment" systems, DOE told Congress.

The entire complex "will also be protected with an aircraft early detection system and a helicopter landing avoidance system," DOE said.Staff writer Don Oberdorfer contributed to this report.