There are two ways you can increase the "maximum number of output members" in ADROUT
1. Change the directory name and the number of outputs...
recycle CICS
run VLSUTIL format on ADROUT / SCPSUTIL INIT
Note: Once you run the FORMAT/INIT, your old prints will no longer be available. My suggestion would be to print out any output that you still need.
2. Run SCPSUTIL function EXPANDDIR
Note: You will need to make sure that all activity is halted on ADROUT so recommendation is to close the file before you run EXPANDDIR.