The White House has launched a broad new effort to reposition President Reagan on key domestic issues and themes before he plunges into next year's expected campaign for a second term.

From civil rights to the environment, from food stamps to education, the Reagan presidency is being redefined on topics that White House officials fear might become costly liabilities for the president in a reelection campaign.

"A rule of thumb in the campaign is build on your strengths and cure your weaknesses," a senior official said. "That's part of what's going on right now."

In a series of mini-campaigns, conceived in the White House West Wing and then played out by the president in speeches, ceremonies and political forays across the country, presidential advisers are trying to erase or soften some of the negative public images Reagan has acquired in his first 2 1/2 years in office.

For example, the president whose environmental views were symbolized by the pro-development crusade of Interior Secretary James G. Watt is to be presented as caring deeply about preserving national parks.

"If there is a strategy, it is to make sure, as they did in 1980, that people realize that in fact Reagan is not a nut, that he's a moderate on the environment, that he's not the caricature of Jim Watt," one official said.

Likewise, the president who virtually ignored education for the first two years of his term has now seized the issue as a demonstration of his commitment to good schools and basic family values.

The president who asked Congress for budget cuts in food stamps for the poor may soon be presented as a compassionate chief executive who worries about hunger.

"There has been a certain amount of repositioning going on, hasn't there?" a senior White House official said last week.

The realignment began a few months ago with a coterie of top presidential assistants. The group has no formal structure, but includes chief of staff James A. Baker III, his deputy, Michael K. Deaver, Cabinet secretary Craig L. Fuller, communications director David R. Gergen, political director Edward J. Rollins and presidential assistant Richard G. Darman. Deaver, who controls the all-important presidential scheduling, is the "driving force," according to several others in the group who discussed the scope of the effort last week on condition that they not be identified.

In their early planning, these officials concluded that the economy would be the foremost issue for 1984 and that recovery would be Reagan's most potent theme in a reelection bid.

But they also identified other issues on which Reagan could be vulnerable, and still others that he could exploit. They likewise pinpointed key constituencies, such as Hispanics and women voters, that should be targeted by Reagan.

The goal now is to engage Reagan in this early groundwork before he leaves for the Far East in November. The president already has plunged into the education issue and has opened an offensive on civil rights. He also is trying to answer the "fairness issue"--the charge that his programs have inordinately hurt the poor and disadvantaged.

In mid-August, Reagan is to stage a week or more of Hispanic-related campaign events. He also is expected to deal with the "gender gap"--the fact that women have given him lower approval ratings than men in public opinion polls. Later, he may delve into issues such as the environment and hunger, on which Democrats are sure to take the offensive.

The campaign planning for these themes already is under way. Cabinet members, who will play a visible role in the repositioning effort, were told recently to plan on devoting at least two days a month to campaigning for the White House, with more emphasis on issues than in the 1982 midterm congressional campaign, according to administration sources.

The redefining effort involves a mix of both policy and public relations.

Two weeks ago, for example, the Justice Department suit charging that Alabama had maintained a racially discriminatory college and university system was filed to coincide with other White House civil rights activities.

Last week, attempting to demonstrate his concern for high black teen-age unemployment, Reagan stepped into the broiling sun of the White House Rose Garden to present Mayor Marion Barry with an $800,000 check from Labor Department funds for summer youth employment in Washington.

Positioned behind Reagan as the television cameras recorded the scene was a group of teen-agers that included Quintin Boardley, 18, still wearing his Safeway uniform.

Only a few hours earlier, Boardley had been hastily recruited from his job at the Safeway store at 14th Street and Kentucky Avenue in Southeast Washington. Larry Johnson, a Safeway official, said he "scouted up" three teen-agers from different Safeway stores for the White House ceremony at the request of the Food Marketing Institute, a trade association.

Safeway participates in a federal tax-credit program designed to spur hiring of disadvantaged teen-agers.

The event was staged primarily for the images it would produce. The next day, a senior White House official expressed disappointment that his edition of The Washington Post didn't carry a photograph of the president handing Barry the check with the teen-agers standing behind him.

Even so, the official maintained that the event "wasn't overreaching." He said: "It was clear if he had gone across the street to City Hall, it would have gotten more attention. But then maybe it would have been seen as something nonsubstantive."

Although they won't advertise it, Reagan's top aides realize that preparing him for 1984 requires shifting gears on many issues, a process that has been under way for some time on potential campaign themes.

"There are some things that will fall away," a White House official said, "and there are new ideas we'll grab a-hold of."

This was illustrated in the education push, considered a prototype for other thematic efforts to come. Reagan quietly abandoned his 1980 pledge to abolish the Department of Education, which faced solid congressional opposition.

At the same time, he seized on the issue of merit pay for teachers, an idea that carried strong support in public opinion polls, as a symbol of his desire to improve the schools.

There have been other shifts, as well. The administration's early civil rights actions included the ill-fated nomination of Philadelphia radio evangelist B. Sam Hart to the U.S. Commission on Civil Rights; a proposal, later overturned by the Supreme Court, that would have given tax breaks to schools that discriminate; and a long delay in agreeing to extend the Voting Rights Act.

Now, taking a different approach, the administration has sent registrars to Mississippi to register black voters, selected controversial but well-credentialed nominees for the Civil Rights Commission and announced a push to strengthen the fair housing laws.

In another example, White House officials said they realized that tighter Social Security disability review procedures were contributing heavily to the perception that Reagan was .nfair to the disadvantaged. The administration moved to soften the harshness of the procedures--and limit the political damage.

"We had to cut our losses and come back with a program that seemed to make some sense," a White House official said. "We've tried to deal with that."

By appointing two presidential commissions, Reagan made still other accommodations with an eye toward next year's campaign. On Social Security, an explosive political issue that hurt the GOP in 1982, he went along with a payroll tax increase in exchange for benefit cuts. On the MX missile, he pledged cooperation with Democrats on arms control in exchange for congressional support for the missile.

Other less-heralded moves bear the marks of pre-1984 politics. Although ostensibly committed to free markets and deregulation, the White House has sidetracked legislation that would abolish the Interstate Commerce Commission--in part because of opposition to the measure from the powerful Teamsters union, which Reagan is courting.

The one area where pre-election politics dictates rigidity is budget and taxes. The White House has put out the word to administration officials not to discuss any tax increases as Reagan heads toward the campaign. And Reagan is planning to stick by his strategy to veto any spending bills he considers excessive.

Looking back on Reagan's education drive, White House officials say they believe it was successful because the president sustained a constant drumbeat on a single theme.

"That was the lesson we learned from it. You don't just pick up an issue and put it down. You pick it up several times until the press is exhausted," one official said.

On the environment, the White House does not yet plan a comparable full-court press, even though Democrats are likely to attack Reagan in the wake of the abuses that turned up in the Environmental Protection Agency scandal earlier this year.

Speaking of the environment issue, one key member of the Reagan team said: "I think it can be neutralized, but I don't see it becoming a plus for us. I think we've got to show we are willing and able to protect people from some of the more egregious effects of pollution, especially toxic waste. Toxic waste is the key. Air pollution would be second."

Within the administration, EPA chief William D. Ruckelshaus is the point man for the repositioning effort on the environment. Ruckelshaus has made toxic waste and acid rain highly visible priorities of the administration, and taken a far more polished approach than did his predecessor, Anne M. Burford.

Although in many ways they were carrying out the Reagan mandate, both Burford and Watt "never were very swift on the image stuff," an administration official said.

"The single gesture of picking Ruckelshaus was the thing," he added. "He is expected to change the image."

Even the often-confrontational Watt can be expected to take a more conciliatory line as the election draws near, the official added. "Nobody has to tell him, he can see it." For example, Watt, who since 1981 has sharply curtailed the government's purchase of park land, recently raised the prospect of millions of dollars in such purchases in the future.

On another topic, there is talk in top White House councils about addressing hunger as a campaign theme. "That issue is kicking around," one presidential adviser said. "We have been very much aware that is a soft issue that the Democrats are beginning to pick up on."

Reagan, stung by criticism that his programs had increased hunger in America, personally wrote a section of his Saturday radio speech two weeks ago to rebut the charge, one official said.

Still, aides say the hunger issue is problematical as a campaign theme for Reagan because he did propose budget cuts in the food stamp program. "Maybe what we should do now is try to do something positive, and then look back on it," one Reagan political adviser said.

On a broader scale, however, the entire range of fairness issues is expected to get heavy attention in redefining Reagan's public image. In the first half of the Reagan term, White House officials say they believe they miscalculated how much of a political liability the issue of fairness to the poor and disadvantaged would become.

"One of the prices we were going to pay for cutting the budget was the charge of unfairness," one official said. "But I don't think anyone realized how deep those charges would go. They have crystallized around the fairness issue."

Now the White House is trying to repair the damage. "We're committed to fairness," Reagan wrote in his radio speech two weeks ago, "and we'll continue to take actions needed to bring it about throughout our society."