Bruno Senna has admitted he is hoping to be retained by Renault for 2012.Senna stepped into the black and gold R31 earlier in 2011 to replace Nick Heidfeld, who had been signed as injured regular Robert Kubica's initial substitute.Senna, 28, has had mixed form during his seven races so far in 2011, describing his season as "interesting" on Brazilian SporTV.Senna said: "In terms of learning, it has been very difficult."I started in the middle and had to learn to use KERS and the moving wing (DRS), and the lack of experience and mileage impaired me a little," he said.KUBICA RETURN?His thoughts are already set beyond the season finale, with his mother Viviane revealing that they are in negotiations with Renault for 2012."I have no contract with any team for next year. The intention is to stay at Renault," he added, referring to the Enstone-based team that in 2012 will be called Lotus.Senna said: "In Formula 1 it is all about performance, and the team is happy with mine."I am trying my hardest to stay in this seat. It depends on (Robert) Kubica, on (Romain) Grosjean, on sponsorship, a lot of things that, unfortunately, are not under my control," he said.Speaking on Kubica's possible return to F1 in 2012, Senna said: "The team isn't going to wait until the middle of next year to decide. I hope it doesn't take too long."