ATLANTA — The preliminary unemployment rate in metro Gainesville rose to 6.9 percent in December, up four-tenths of a percentage point from 6.5 percent in November, Georgia Department of Labor announced today. The rate was 7.5 percent in December 2011. The jobless rate rose because of a combination of factors: a slight increase in new layoffs represented by initial claims for unemployment insurance benefits, a loss of jobs and a reduction in the labor force.