Nat Danas is a legend in the world of auto interior trimmers. Danas founded Auto Trim & Restyling News, a magazine now owned by Bobit Business Media (It's a great read if auto upholstery is one of your interests).
When the economy got bad, Nat always told the story of a man who advertised his hot dog stand with a sign that had several hundred light bulbs. The advertisement sold lots of hot dogs and helped the man raise enough money to send his son to business school. After the son returned home he said, "In school they told us a recession was coming and businessmen like you should cut their light bills." The father got rid of his advertisement and his business immediately dropped off to almost nothing.
"See," he told his friends. "My son is smart; he learned about the recession in school and knew my business was going to drop; I'm so lucky he told me to turn off that lighted advertising sign before the drop."
Nat thinks it is important to keep advertising during downturns. If you promote when everyone else stops doing so, you'll wind up with a bigger slice of the pie and when the market grows again, you'll most likely retain that bigger slice of market share. This worked for me when I was the publisher of Old Cars Weekly in the '80s and I know it will work today.