Japan revised its spending on defense for next year, taking into consideration its relations with Washington, according to government sources. The government decided to spend a total of $11.5 billion on defense in fiscal 1981. This is 7.61 percent more than the current financial year and 1.01 percent higher than a provisional defense spending figure set by the Finance Ministry last week. But the 7.61 percent increase is still less than the Defense Agency's original request of a 9.7 percent increase. The United States, which has a security treaty with Japan, had demanded the 9.7 percent increase.