Some 61 percent are also working to use different metrics to track DC plan success – more than just participation and deferral rates, they are working to help their employees better evaluate their retirement readiness, a figure that's jumped from 50 percent a year ago.

And 86 percent of those surveyed say they plan to focus their communications efforts to help employees better understand and figure out ways of planning how much they need to save for retirement.

Target-date funds have also grown as an easier and more straight-forward method for workers to do their 401(k) investing, with 76 percent of plan sponsors interviewed providing TDF options, and 35 percent saying they will add them in 2013.

Managed accounts and online third-party advisory services have also grown in popularity.

Approximately 28 percent of companies surveyed say they provide in-plan annuity options – "retirement income solutions" – almost double the number that offered the services a year ago. Thirty percent of those surveyed who don't have annuity options say they would like to add them in 2013.

"To ensure that a worker's investment risk exposure appropriately matches their needs given their age and other factors, it is critical that 401(k) investors periodically rebalance their portfolios," said Patti Balthazor Bjork, director of retirement research with Aon Hewitt.

"However, we know that most rarely, if ever, do so because they are overwhelmed or unsure about their investment choices,"

Other key findings from the survey:

• 52 percent of companies will use podcasts and 42 percent will use text messages to communicate and educate their workers on their retirement benefits in 2013.
• The percentage of plan sponsors that plan to use social media channels to communicate with workers has tripled from 6 percent in 2012, to 18 percent in 2013.
• 37 percent of employers have recently reviewed the total DC plan costs (fund, recordkeeping, and trustee fees). Among those who have not, 95 percent are likely to do so in 2013.
• 35 percent of employers completed a review of DC fund operations, including fund expenses and revenue sharing; 87 percent plan to do so this year.
• 31 percent of employers recently changed their DC plan fund lineup to reduce costs. More than half (52 percent) of the remaining companies may do so in 2013.