Don't plan for retirement; plan to keep working
If you're in your mid-50s, you've probably started to consider when, exactly, you will retire. Working longer means you not only extend the years you are adding to your retirement savings, but it reduces the number of years you need your savings to support. In the example above, working in the same job for another three years, until you are 65, reduces your gap to $1,900 a month.
What if you're burnt out? If you start planning now, you may be able to find a middle road, a second career into which you can transition in your early or mid-60s. In addition, if you delay taking Social Security, the government will increase your monthly benefit. If you are 55 (born in 1958), delaying retirement until age 70 will increase your monthly Social Security benefit by about a quarter, so that if you were set to get $1,000 each month, you'll get $1,267 instead. Social Security offers a website to help you figure out how much of a difference delaying will make.
(Read more: Six feet under as a retirement plan)
Stay in equities longer than you may think 'safe'
"Do not think you're going to invest your way out of this," said Harold Evensky, an investment advisor whose firm, Evensky & Katz LLC, is based in both Miami and Lubbock, Texas. But if you're shifting your planned retirement date, you also should extend the time frame of your investment portfolio. You can increase the chance that you'll earn a higher return by staying in equities for longer and in a greater proportion. Also, in this environment many experts say that bonds are a riskier investment than they usually are, because the government has been keeping interest rates artificially low.
In the post–World War II era, when interest rates rose after a long period of artificially low rates, bondholders lost money. "Since you will probably live to about 85, do not go into bonds until you are about 70, and then only gradually," said Charley Ellis, a consultant to governments and large institutions and a former board member of Malvern, Pa.–based Vanguard Group. (The average life expectancy for Americans is between 80 and 85).
Tap your house as an asset sooner rather than later
If you sell your house and downsize, you'll be able to use the proceeds to add to your retirement savings, tax rules permitting. You'll also be taking a huge step toward reducing your monthly expenses. Selling a house is an emotional decision for many. But if you believe you'll have to downsize eventually, the sooner you can practically make the move, the better off you will be.
—By Elizabeth MacBride, Special to CNBC.com