President Reagan, marking the approaching anniversary of his year-old Middle East peace initiative, asserted yesterday that the plan "definitely is alive" and remains "the only realistic basis that has thus far been presented" for resolving the Arab-Israeli conflict.

The president used his weekly radio address to stress that U.S. policy in the region still is based on the initiative he announced last Sept. 1. So far, however, the plan, which called for the Israeli-occupied West Bank and Gaza Strip to become independent "in association with Jordan," has failed to make any headway against the opposition of Israel and the Arab world.

That was acknowledged by Reagan, who said, "Unfortunately, the opportunities afforded by our initiative have yet to be grasped by the parties involved."

Administration officials said that the president, who also referred to the initiative in a Friday speech to a Republican women's group, wanted to make clear that he will not abandon attempts to win acceptance for the plan. The administration is reshuffling its Middle East policy-making team, and the officials said the new group shortly will begin a comprehensive review of ways to break the stalemate.

What will emerge is not clear, officials conceded. But, they added, Reagan and his senior advisers felt it important to use the impending anniversary to counter suggestions that the initiative is dead and that the administration is weighing major shifts in its Mideast policy.

The officials pointed to one passage in Reagan's statement that criticized Israel for continuing to erect settlements on the West Bank. The president said:

"The establishment of new Israeli settlements in the occupied territories is an obstacle to peace, and we're concerned over the negative effect that this activity has on Arab confidence in Israel's willingness to return territory in exchange for security and a freely and fairly negotiated peace treaty." His words seemed intended to ease Arab concern about the American veto early this month of a U.N. Security Council resolution that would have imposed trade sanctions against Israel if it failed to dismantle the settlements.

That resulted in Arab complaints that the United States is easing its opposition to Israeli settlements policy, and the Knight-Ridder newspapers reported on Friday that such a move is being debated in the administration.

The officials said yesterday that they did not know whether Reagan's criticism of the settlements was meant to answer the Knight-Ridder report. But they disputed the report's contention that Samuel W. Lewis, the U.S. ambassador to Israel, has argued that the settlements' expansion has gone too far to be reversed and that the administration should permit Israel to put into effect its plans for limited Palestinian autonomy in the occupied territory.

Lewis is understood to have warned that as more settlements are built, the realities of Israel's internal politics will make it increasingly difficult for any Israeli government to back away from the contention that the West Bank and Gaza must remain under Israeli control.

But, the officials insisted, there has been no serious discussion at senior levels of the administration about accepting the Israeli position or abandoning Reagan's proposals for the future of the occupied territories. In fact, the officials added, the West Bank has been on the back burner during recent months as the administration focused on the more immediate problem of trying to get Israeli and Syrian forces out of Lebanon.

The Associated Press said that Israel Radio reported in Tel Aviv yesterday that Israeli diplomats managed to get Reagan to soften what was to have been a stronger policy statement. The radio reported Reagan originally planned to denounce Israel in stronger language and to urge Israel to accept the principle of withdrawal on all Middle East fronts.

White House spokesman Larry Speakes, in California with the vacationing president, said he was "unaware of any such involvement by Israeli diplomats in the preparation of the radio address."

The impending redeployment of Israeli forces to southern Lebanon still has the State Department and Reagan's new special Mideast envoy, Robert C. McFarlane, concentrating on a search for measures that will prevent a new escalation of civil war between Lebanese Christian and Druze militias after the Israelis pull out of Lebanon's Chouf Mountains. However, the officials said, the recent policy-making reshuffle, which included the appointments of McFarlane and of Richard W. Murphy as assistant secretary of state for Mideast affairs, means that Secretary of State George P. Shultz will have to sit down soon with the new team for a comprehensive review of how the administration might get its stalled initiative moving again.

That is not likely until sometime in September since Reagan and Shultz are on vacation, McFarlane is shuttling through the Middle East and Europe on the Lebanon situation and Murphy is en route to Washington from his former post as ambassador to Saudi Arabia. But, the officials said, within the next month they will have to begin pondering in earnest how to achieve the "creative and persistent diplomacy" that the president yesterday said is necessary "to end this tragic and bitter conflict."