The Cod Army signed off from this campaign with a 2-1 defeat at AFC Wimbledon - who secured their League Two status in the process - to finish in 13th place, nine points off the play-offs.
Alexander said: "We have way too many players at the moment. We'll be looking to carry about 10 less so there will definitely be players leaving.
"We have to make sure we can bring in players with the right character and mentality for this division because I think we have the ability but we're lacking in the mental and physical side.
"I don't think it was a definite penalty, I think it was an opportunity to give a penalty. I'm not begrudged by the result but the referee was swayed by their crowd, a lot of free-kicks went their way.
"I thought we lacked discipline in the second half. The effort was there but I think we have to get a bit more streetwise.
"We have identified some players and we know where we need to act. I won't be having a break, while we have this period of no games I need to do everything to make sure we are competitive for next season."