Use of exec command in a script

Guru's,
I want to make a use of "exec" command in my script and want to check return code of executing script, but as you know exec command will terminate current processID and comeout and will trigger new one, i am unable to check return code of script and not able to run a scrpit after exec.
so can you please help me to fix or give alternative to trigger a script.

Basically i am trying to check add a check whether script A is running or not if NO then it will trigger another instance of same script.

Script :

#!/usr/bin/ksh
LOG_FILE=/GEM_PILOT/custom/script/cx_log
SERVER="${HOSTNAME}";
USER=`whoami`
CURRENT_PROCESS_ID=" ";

if [ -n "${SERVER})" ]
then
  while read LINE
  do
    if [ `echo ${LINE} | cut -c1` != "#" ]
    then
      DIR=`echo ${LINE} | cut -f1 -d"|"`;
      cd $DIR
      SCRIPTNAME=`echo ${LINE} | cut -f2 -d"|"`;
      ISEXECUTABLE=`echo ${LINE} | cut -f3 -d"|"`;
      DESC=`echo ${LINE} | cut -f4 -d"|"`;
    fi
    if [ -n "${SCRIPTNAME}" ]
    then
      CURRENT_PROCESS_ID=`ps -ef | grep "${SCRIPTNAME}" | grep -v grep | grep "${USER}" | grep "1" | tr -s ' ' ' ' | cut -c2- | cut -f2 -d" "`;
      if [ -z "$CURRENT_PROCESS_ID" ]
      then
        cd ${DIR}
        exec  $SCRIPTNAME;
        RET=$?;
        if [ "${RET}" -eq 0 ]
        then
           NEW_PROCSS_ID=`ps -ef | grep "${SCRIPTNAME}" |grep -v grep | grep "${USER}" | grep "1" |  tr -s ' ' ' ' | cut -c2- | cut -f2 -d ""`;
          if [ -z "$NEW_PROCSS_ID" ]
          then
            echo "$SCRIPTNAME has successfully started with ProcessID ${NEW_PROCESS_ID}" >> $LOG_FILE
        mailx -s "$USER instnce of $SCRIPTNAME restarted with ProcessID $NEW_PROCSS_ID" test@xyz.com
          fi
      fi
      fi
      echo "$SCRIPTNAME is already running with $CURRENT_PROCESS_ID SPID" >> ${LOG_FILE};
    fi
    done < /GEM_PILOT/custom/script/test.dat;
fi

Delete the word "exec".

Regards,
Alister

Allister thank you for replying, i tried removing exec command, it's triggering script, but command followed after those are getting bypass and not getting execute.
I want to execute those as well and send alerts to team