Just a year ago, as he prepared to deliver his first State of the Union message in better times for his presidency and for the country, President Reagan fondly recalled his acting days. "You know," he told a reporter, "I've always described it that in Hollywood if you didn't sing or dance, you ended up as an after-dinner speaker about the things that I feel should be corrected."

He then proceeded to deliver an address that was so flawless a performance and seemingly so casual a delivery that for months afterward many people refused to believe that he had read it verbatim from two TelePrompTers positioned before him in the well of the Congress.

Last night, the scene was the same, and his after-dinner arts were again on display for the nation. But last night, while the performance was again formidable, the message could not have been more different.

He took as his text his old hero, Franklin D. Roosevelt, and in as delicate a political maneuver as FDR himself performed, blithely shifted course as easily as the master had done in a different but nonetheless difficult period.

Roosevelt simply had declared Dr. New Deal dead and Dr. Win the War firmly in vogue when it suited his purposes. Reagan approvingly evoked Roosevelt's admonition that "the future lies with those wise political leaders who realize that the great public is interested more in government than in politics." He thereby tacitly aligned himself with the example of a president who expanded powers of government in economic crisis.

Uses of government wound their way through Reagan's second report on the state of the union. In a time of economic hardship, he said the challenge was on the government "to ease this massive economic transition for the American people."

He spoke of the need for jobs and retraining programs, something he had avoided studiedly, of government assisting states in new education programs, of government helping farmers, of government taking the lead to provide new legislation "to provide catastrophic illness insurance coverage for older Americans."

The single line in his 45-minute speech that brought the most emotional reaction was his declaration that "we who are in government must take the lead in restoring the economy." That brought the Democratic side of the aisle to its feet in thunderous applause, whoops and yells, causing the president to quip, "And here all that time, I thought you were reading the paper."

And as if to underscore how far this president had traveled since he last reported on the nation's state, the theme that dominated his address a year ago received a cursory mention this time .

His so-called New Federalism, which he then described as "our next major undertaking" and one that would be "bold and innovative" now that NEWS ANALYSIS his economic program was securely in place, received only one vaguely worded sentence buried at the very end of his domestic proposals.

There was also a different tone and feel in the House chamber as the new Congress assembled to hear what Reagan had to offer about the country's future course. As a rule, State of the Union messages are seldom memorable.

They are usually optimistic and usually dull, a laundry list of self-proclaimed administration achievements and promises of great things that lie ahead. They rarely touch off a spark of interest and rarely are remembered.

Last night's was different from the norm in several respects. The economy had continued in a tailspin for a year. Unemployment had continued to rise, bankruptcies and farm foreclosures had multiplied and so had the national deficits. The political climate had changed dramatically and with it the fortunes of Ronald Reagan.

Where just a year before he was boasting a 60 percent approval rating in the latest polls, the same pollsters on this day had shown him dropping even below the hapless Jimmy Carter at the same time in office. And gathered before him were 52 new Democratic members of Congress, presumed to be more practical and desirous of greater governmental efforts to combat the deepest recession since the 1930s.

Even for all of his considerable skills at speech-making, Reagan faced a difficult task of political persuasion. His approach and speech reflected that awareness. Gone were the easy claims of economic success of a year ago.

"The program for economic recovery that is in place will pull the economy out of its slump and put us on the road to prosperity and stable growth by the latter half of this year," he said then. "And that is why I can report to you tonight that in the near future, the state of the union and the economy will be better--much better--if we summon the strength to continue on the course that we've charted."

Gone were the forecasts that deficits would be reduced "steadily, surely, and, in time, completely." A year ago, he spoke of deficits starting at less than $100 billion and declining. Last night, he spoke of facing the prospect of $1 trillion worth of new debt in only a few years if drastic changes were not made.

Gone were the flat promises never to raise taxes. While he stood by his scheduled tax cuts of next summer, he also told the country that he was proposing a standby tax to insure bringing down the deficits in years to come.

What remained constant was Reagan's skill at delivering a message, however changed in character. On the basis of his performance last night, he still stands as the nation's best after-dinner speaker.

The question is whether his audience, in the small, packed congressional chamber and in tens of millions of homes around the country, will find his new rhetoric as persuasive as his performance.