Actually, I'd suggest using a symbolic link. It will point all request of olddirectory/wp-content-uploads to /wp-content/uploads
ln -s [path]/wp-content/uploads [path]/olddirectory/wp-content/uploads
Above command will create a symbolic link to the folder you want.
[path] is your full server path. /var/www/vhosts/ etc etc...Ask your host tech support if you dont know what it is.
I do this through command line through ssh access (I am unsure if there are any FTP programs that do this for you). If you dont have such access, I'd suggest asking your host tech support to help you out.
I hope this helps (and I'm right).
edit: so, basically...you a enot altering the database, but asking the server to re-route the requests.