If at first you don't succeed, the old saw goes, try, try again.

The Watt regime at the Interior Department apparently believes in old saws. They fired John R. Gingles the other day, for the third time in a year and a half.

The pink slip that floated across Gingles' desk Nov. 24 told him that as a result of fiscal 1983 budget cuts and reduced staffing needs, "it is necessary to eliminate those positions considered excess to authorized requirements."

The words had a haunting familiarity for the 39-year-old bureaucrat. Twice he has argued successfully that it is not his National Park Service position that is considered "excess," it is him.

Gingles is a Carter administration holdover of the first order, a congressional liaison for former secretary Cecil D. Andrus who gave up his political appointment for a career slot just seven months before the White House changed hands.

Secretary James G. Watt's first attempt to dislodge him, in May, 1981, failed when the Merit System Protection Board's office of special counsel intervened and ordered Gingles reinstated to his job in the park service's office of legislation.

Last June, Interior tried again, but succeeded only to the extent of getting Gingles downgraded to a job in the park service's land acquisition office, not a hotbed of activity these days, considering Watt's policy of not acquiring any more parkland. "A non-job," Gingles describes it.

Gingles, who by this time almost qualifies for his own key to the supply closet at the special counsel's office, has requested another investigation.

Meanwhile, it may be a tad early for Interior to be claiming budget distress. In a budget mark-up session yesterday, the House Appropriations Committee increased funds for parkland acquisition in fiscal 1983, just as it did last year.

Will Gingles' office suffer from reduced funding levels? "Not if our bill goes through," said a committee aide.