The Blues have scored just once in three winless games since Benitez's arrival and Fernando Torres continues to endure a miserable spell with just one goal in his last 11 appearances.
Lukaku struggled to make an impact at Chelsea following last summer's switch from Anderlecht, but the 19-year-old has impressed during his loan spell at West Brom, netting five goals, including two in the last three games.
His fine recent form has led to speculation that Benitez could trigger a clause in the deal to recall the £18million signing next month, but the Spaniard has suggested he will let Lukaku continue to learn his trade at The Hawthorns.
"We know Romelu has been doing very well for West Brom," he told The Sun.
"But it's maybe best for him to stay there where he is playing games for now, as it will be better for his future development."
Lukaku has admitted he is keen to stay with the Baggies for the whole of the season-long loan spell.
Speaking recently, he told Wolverhampton Express and Star: "I don't think about the option. I am very happy to be here for one year.
"Hopefully, this season will end very well and we will see what happens in the future."