Chenene, an off-season signing from Moroka Swallows, has netted twice in three Premiership outings this campaign, most recently scoring in the 3-1 victory over champions Kaizer Chiefs on August 31.
The 29-year-old also impressed with 10 League goals last term.
"Everybody says Bennett is the signing of the season for United, but I think he's got more to offer than he's doing currently," Johnson is quoted as saying by the Premier Soccer League's official website.
"I think he did a lot better at Swallows and he still has to learn or understand the players that are around him now.
"At SuperSport we ask a little bit more, we ask him to track back. It's the third game, I think he'll get better," concluded the ex-Platinum Stars mentor.
Meanwhile, Chenene has revealed he has set himself a 15-goal target.
"I hope to continue this season where I left off last season - working hard, and helping the team by scoring as many goals as I can. I have set myself a target of 15 for the season," he said.
On his form, he added: "Nothing has changed with me, it’s just been about hard work, playing regularly and gaining in confidence with more game-time."
