The run-up in stock prices this year could tempt even the most hands-off investor to wade into their 401(k) and make some changes. But experts suggest investors tread cautiously and avoid major changes aimed at timing the market.

Even if you’re a set-it-and-forget-it type, unless you’ve pulled out of stocks completely — as some did after the 2008 financial crisis — it’s likely the stock portion of your 401(k) has grown significantly.

Data released Thursday by Fidelity Investments show the average balance of its accounts hit a record high in the first quarter of $80,000, up 75 percent since stocks hit bottom in early 2009.

In contrast, some 1.6 percent of investors 55 or older who dumped stocks from their portfolios when stocks collapsed in 2008, and never rebalanced their holdings, saw their portfolios grow just under 26 percent over that period, Fidelity said.

Here are ways to efficiently manage your 401(k):

KNOW THE BASICS If your company offers to match up to a certain amount of your contribution, put away enough to get the maximum.

And save as much as you can, as early in your working years as you can. Experts vary on how much, but a common benchmark is 15 percent, including any matching funds. The maximum contribution the IRS allows is $17,500 this year.

BE COMMITTED: The market rises and falls, and timing may not be on your side. One way to maximize savings is to put more money into the plan.

“Those who continued to not just remain invested, but remained committed to making contributions, are the ones that were able to come out ahead in the end,” says Beth McHugh, a vice president at Fidelity.

LOOK AHEAD, UPDATE: Making sure you’re financial needs are met in retirement requires having a sense of what those costs will be. And not just the basics, but any travel or other major purchases. You’ll also need to update that plan, particularly as you get closer to your post-work life.

By some estimates, retirees will need 85 percent of their pre-retirement income coming in from several sources, including Social Security, 401(k) plans and other sources.

“If you’re behind saving or want to retire at an earlier age, you may find when you crunch the numbers that to reach your goal you should be saving 15 or even 20 percent,” says Eric Tyson, author of “Personal Finance for Dummies.” “If you’re at a point in your earnings career where your earnings are relatively high but you don’t think it’s going to last ... you may want to save 20 percent to 25 percent of your income during a certain period.”

A bevy of calculators are available on the websites for big 401(k) firms like Vanguard, Fidelity and T. Rowe Price. A couple of alternatives: The AARP’s calculator and Bankrate.com’s.

TWEAK: Experts recommend taking a look at your asset mix — how much you have invested in certain funds of varying risk or, say, the proportion in stocks vs. other assets — and tweak them occasionally.

“Whether the market is up or the market is down, it’s always a good time,” says Philip Rousseaux of Everest Wealth Management. “It’s kind of an automatic way of always selling high and buying low.”

If you’re heavily invested in a segment of stocks that have gone up sharply, you bring down your position on that a bit and shift the funds over to a segment that’s undervalued. Rousseaux recommends rebalancing at least on a quarterly basis. Tyson says every three to five years is fine unless the market has undergone a significant downturn.

As a general rule, stocks are going to be more volatile and risky in the short term, but reduced over the long term. With bonds, it’s reversed.

RESIST TIMING URGE: Experts suggest avoiding major changes to profit off a market trend. “Market timing changes people make are often made on emotional reactions to events,” Tyson says. “It’s better to have an overall allocation, and stick to that.”

If you do take a shot and miss, don’t wait for a time to jump back into the market.

PLAY CATCH-UP: A 2006 law allows workers over 50 to beef up how much they contribute to their 401(k) plans and other retirement accounts. This can be helpful if you’ve incurred a big loss.