If you have a fuel filter that is in-line with the fuel line under the chassis, yes, it should be replaced. If your filter is inside the gas tank, this is replaced when the fuel pump needs replacing.
Subaru suggests you replace the fuel filter at around 90,000 miles. This interval is generally when you might have clogging problems. You can follow their guidelines or wait until you have a problem, which will be when your car won't start because fuel cannot get to the engine.
〉 Answered on Feb 23rd, 2015 by Gail Dunn, Owner at Women's Automotive Connection