Some Republican insiders expect President Reagan finally to pass the word that he will be running for a second term when he meets his strategists in Los Angeles on Aug. 21 for what is officially billed as "an update" on the organizational progress of his undeclared campaign.

Though the advisers are proceeding on the assumption that Reagan will run again, the president isn't in any hurry to announce. Advisers who worried a few months ago that presidential silence would fuel the suspicion that Reagan will walk away from the White House for the solitary pleasures of his mountaintop retreat northwest of Santa Barbara now say they believe they have overcome the doubts of all but the heartiest skeptics. And they think the signal Reagan may give in August could convince even them.

"We expect the president to tell us that he hasn't decided yet, but he likes his job," one member of the Reagan inner circle said last week.

Whatever Reagan says, his strategists are proceeding on the assumption that subsequent actions will speak louder than words. The Sunday meeting will mark the start of a week of political travel, after a week's vacation at the ranch, that is indistinguishable from a reelection campaign. It includes two appearances before Hispanic groups in Los Angeles, an education speech in the same city, an address to the American Legion in Seattle and a "women's speech" in San Diego.

Another clue emerged from a presidential decision, recommended by White House chief of staff James A. Baker III, that Reagan should delay vacationing for a day and add the Veterans of Foreign Wars to his August speaking schedule. The VFW, which in 1980 broke with its nonpartisan tradition to endorse Reagan for president, was in a white heat because the White House had ignored a previous promise and turned down the speaking request.

White House officials said that Reagan, who doesn't bother with such details, had not been aware of the rejection. He readily agreed to fly back to New Orleans from Mexico for the Aug. 15 speech before going to the ranch.

"The VFW is important to him," said Cabinet secretary Craig L. Fuller, who helped arrange the schedule reversal. "The VFW has been very supportive of the president's Central America policy. They've been very supportive of his campaigns."

Though the full cast hasn't been selected, the Los Angeles campaign meeting may include a somewhat larger group of participants than earlier meetings. The core group includes Sen. Paul Laxalt (R-Nev.), the campaign chairman, veteran strategist Stuart K. Spencer, White House staff chief Baker, deputy chief of staff Michael K. Deaver, pollster Richard B. Wirthlin and political director Edward Rollins.

Among other things, Reagan's advisers are expected to tell him that five regional directors have been selected for the second-term effort. These include former representative John Rousselot (Far West), Rick Shelby (Southwest, including Texas), Lou Kitchin (South), Paul Manafort (Midwest) and Roger Stone (East).

Reagan operatives expect a reelection committee to be formed before he leaves for a five-nation tour of Asia in November. He's scheduled to stop off at the ranch once again before an announcement of candidacy in late November or early December. Such are the joys of the presidency.

The bad news for Reagan is that his Central American policies score highly unfavorable votes in all the polls. The good news, if it can be called that, is that most Americans don't know much about Central America.

Despite the president's nationally televised appearances, most Americans still aren't clear that the Salvadoran government is supposed to wear the white hat and the Nicaraguan government the black one. Reagan pollster Wirthlin says this is because Central America hasn't been a front-line issue until recently.

"People can tell you where the Panama Canal is but they can't identify the countries bordering it," Wirthlin said.

Looking into his crystal ball, Wirthlin believes that economic isues are likely to be dominant in 1984. "Regardless of past votes or partisanship, those who think the economy is getting better are likely to support the president and those who don't are likely to oppose him," said the veteran pollster.

U.S. Ambassador to Nicaragua Anthony Quainton took the lead role in toning down the president's condemnation of supposed Nicaraguan anti-Semitism. Quainton told the White House that some accusations couldn't be proven and they were eliminated from Reagan remarks and a White House digest relating administration actions in Central America.

The action caused a furor, prompting some West Wing officials to detect a whiff of anti-Semitism in the basement quarters of the National Security Council, two days before deputy national security adviser Robert C. McFarlane was named as special envoy to the Middle East with a responsibility for trying to involve the Syrians in the Lebanese peace process.

White House officials claim that the McFarlane issue has nothing to do with the decision. They argue that it simply isn't desirable for the president to be making questionable statements about Nicaragua at a time he is trying to demonstrate that he favors the peace process in the region.

Reaganism of the Week: (Speaking to the National Council of Negro Women last Thursday about how the summer youth employment budget had been increased by more than $800,000): "In fact, just last week we found another $800,000 in the Rose Garden. Well, not in the Rose Garden, we're not that careless over here. We found it in the Labor Department."