Bell was going to be substituted before he scored a stunning goal which assisted in City getting a 2-2 draw at Watford on Saturday.
Speaking to the CT, Boothroyd said:" Belly was fantastic against Portsmouth and Morecambe - unplayable at times- but against Watford he didn'nt show enough of that.
"But then he scored the goal, so that will be in the back of my mind, if I ever think of taking him off again.
"David has got a huge amount of talent and so far, to be honest, I think he's under-achieved.
"He's got so much more to give, but he's got to stop playing his football in the middle third of the pitch - he needs to be further up because we have all seen what he can do.
"In the early part of his career, he was a continuity player for wnat of a better word. He gets it and also gives it, but why give it to someone else when you can cause absolute havoc yourself.
"That's all I'm asking him to do and I've said the same to Gary McSheffrey and Freddy Eastwood. I want to look for wins, so I want my forwards to be positive, to get people on the back foot."
Picture copright of Covsupport News Service. Credit CNS/KM