The shilling has lost 1.7 percent since the start of 2015 against the dollar, after a 4.5 percent fall in 2014 that was largely blamed on a downturn in the vital tourism industry after a number of militant attacks.
It was trading at 91.85/92.05 to the dollar on Thursday.
"We did an assessment a few months ago and we found there was an excess of valuation around 5 and 10 percent at that time," said Armando Morales, the International Monetary Fund's representative in Kenya.
A new evaluation was needed "but at this point it is probably going to be around the same levels," he told Reuters in an interview late on Wednesday.
To keep Kenya competitive, the shilling needed to be in the upper 90s to the dollar, Morales said. "People should not get worried if the exchange rate depreciates gradually," he said.
Kenya secured a one-year renewable deal with the IMF last year for a $688 million precautionary credit arrangement to help with any future shocks, although the government has said it does not plan to use such a loan.
Kenya's access to the facility, normally only offered to more developed emerging markets, highlighted its economic "track record" and developed financial market, Morales said, although he said the central bank needed to be vigilant about rising demand for credit and foreign exchange.