The government reported yesterday that retail sales across the nation rebounded somewhat in February after falling off the previous month, indicating the earlier slippage was mostly weather-related and there has been little real slackening in the pace of the economy.

Commerce Department figures showed consumer spending up 0.6 percent over the month to a new seasonally adjusted level of $71.47 billion. Retail sales had edged up only 0.2 percent in January, following two months of unusually sharp increases.

At the same time, the department disclosed that its latest survey of business investment plans shows that American firms have not changed their schedules for modest spending on new plant and equipment. The survey showed capital spending will rise only 3 percent after inflation.

The results jibed with a previous poll made public in January which also predicted a 3 percent rise in real terms. As was the case in the earlier survey, the latest poll also shows the largest increases likely to come in manufacturing industries.

The combination of figures added little new to the conflicting economic statistics that have emerged in recent weeks. The signals appear to show continued rapid economic activity with signs of sharply accelerating inflation.

The figures came as, separately, Federal Reserve Board Chairman G. William Miller told an audience of thrift institution officials yesterday inflation still is the nation's numberone problem and the Fed will continue its tight-money policies to help combat it.

The rebound in retail sales last month was almost entirely in non-durable goods. Sales of non-durables rose 1 percent over the month to an adjusted $46.21 billion, after having remained essentially flat in January.

Sales of durable goods, dragged down primarily by a falloff in auto sales, declined less than 0.1 percent in February to a new adjusted level of $25.27 billion. Sales of durables rose 0.4 percent in January to $25.27 billion.