Ricketts will miss the next three games - including Saturday's League One game against Scunthorpe - after being sent off in Tuesday's Carling Cup first round defeat at the hands of Darlington.
"Losing Michael is a big blow and he is upset about that as much as anyone. He is a quality player with a quality finish as he proved on Tuesday," Mullen told the Express & Star.
"I have looked at the option of bringing in a striker on loan over the last 24 hours, but I also have to look at the situation I have here with our own squad.
"Troy Deeney came on as a substitute on Tuesday to play up front and Alex Nicholls has played in that position before.
"He has pace and an eye for goal and of course Ishmel Demontagnac also has experience of playing up front.
"He rarely scores simple goals for us, they are always screamers and he will also be under consideration."