Liberace the Lucrative leaves town tomorrow richer by his share of a gross of about $450,000 after performing to nine sellout audiences at the Kennedy Center. Liberace the Lavish is poorer by one gold-leaf, 2-foot-square chocolate piano full of truffles, which he sent as a "Glad You're Well" present to President Reagan.

The piano was personally escorted by Marc Randolph, the chocolate sculptor from Watergate Pastry Shop, who took it to the White House yesterday afternoon.

Liberace went to the White House, too, but separately. He, his manager Seymour Heller, his promoter Manuel Levine and several others toured the White House yesterday afternoon after a look at the Capitol with Rep. Bob McEwen (R-Ohio).

Pete Roussel, a Reagan spokesman, said, "We're holding the piano in the residence until the president and Mrs. Reagan are back on Sunday. Then we'll send it up for them to see." In the meantime, the truffled piano is understood to be under heavy guard.

Whether the piano had to go through the metal detection unit or the bomb squad was not revealed. "Whatever is appropriate will be done," said Roussel. A usually reliable source says there were a number of applicants for the job of Official Taster.

Will the president eat it all? The piano lid with the gold-leaf "L"? The gold-leaf scrolled sides? The white and black chocolate keys? Or will he, overcome by the thought of the calories, as was Liberace, give it to someone else? Roussel indicated the decision could only be made at the top.

The confection may end up as the most famous White House piano since Margaret Truman's.