President Reagan continued his war against a House Democratic budget proposal for the second consecutive day yesterday, criticizing the plan as a plot to sacrifice the nation's economic recovery and military security "on an altar of discredited, hand-me-down economic theories."

Speaking on his weekly Saturday radio broadcast, Reagan said the Democratic budget would bankrupt the Medicare system, unlike his administration's budget proposals.

Then he asked listeners if they knew how Democrats plan to raise the $181 billion they would add to the adminstration's budget plan over the next five years for spending on other social programs.

Answering his own question, Reagan, speaking from Camp David, Md., said:

"Two ways: by compromising America's defense security and by slapping massive new tax increases on every working family. Ignoring the Soviets' tremendous advantage in military forces, the liberals would cripple our efforts to modernize America's defenses. To put it bluntly, their budget gambles without security and safety."

Reagan's address followed two speeches Friday in which he lambasted the same Democratic budget proposal. He plans to spend most of his time before Wednesday's scheduled House vote on the proposal battling the plan that would halve the amount of his planned 10 percent increase in defense spending, increase funding for social programs and perhaps wipe out a 10 percent income tax cut set July 1.

On Monday, the president plans two meetings with groups of House Republicans to lobby against the Democratic proposal. On Tuesday, there will be more meetings with Republicans and leaders of the National Association of Manufacturers, which already has announced opposition to the Democratic budget.

Reagan may also make a speech, possibly on television, arguing that the military critically needs the buildup provided in his budget, aides said. In addition, there are plans to have him meet with reporters to stress his budget concerns.

White House aides said Friday that Reagan is convinced that, despite the increased Democratic majority in the House, he can defeat their budget for the third consecutive year because it is too "left-wing" to gain support from moderate Democrats.

Yesterday, the president indicated the outlines of his lobbying plan against the Democratic proposals. He labeled their plan the "so-called liberal Democratic budget" and said it would undo the growing economic recovery and send "the budget, prices and interest rates soaring out of control and our economy into a tailspin."

He then cited what he called the Democrats' lack of attention to the financial problems of Medicare and gave a detailed list of military programs that he said would have to be abandoned if the Democratic proposal wins.

In the Democratic response to Reagan's speech, and specifically the attack on the Democratic budget as a liberal document, Rep. Richard A. Gephardt (Mo.) said, "You don't have to be liberal to respond to clear human needs."