This is basically http://mywiki.wooledge.org/BashFAQ/050 -- assuming your script actually does something with $count
somewhere further down, you should probably refactor that to avoid this antipattern. See the linked FAQ for much more on this topic.
Having said that, it's not hard to do what you are asking here without making changes to live code. Consider something like
awk 'END { print 5 }' /dev/null > file
in a cron
job or similar (using Awk just because your question asks for it, not because it's the best tool for this job) and then in your main script, using that file;
read index <file
count="countshift$index.sh"
While this superficially removes the requirement to change the script on the fly (which is a big win) you still have another pesky problem (code in a variable!), and you should probably find a better way to solve it.