Actually, many shared hosting companies (the good ones, at least) allow you to raise the limit through different methods. Ask your hosting support how to do it, and here's one common way: put this inside your php file (for example, oc_load.php after the first <?php line):
ini_set('memory_limit', '256M');
Then check with phpinfo() or ini_get() to see if it has any effect. There are other ways, server- and hosting- specific, so better ask them to know for sure what and if will work in your case.
Regards