JMP,
You cannot directly jump from 7.1 to 7.5.2 from "Check for Updates". If you upgrade through "Check for Updates", you'll have to update multiple times, as it will go through every major versions(7.2, 7.3, etc...), so you'll have to do this multiple times.
The other option is to uninstall your current version, and then install the latest version. If you start from 7.1, this is actually the quicker option, since otherwise, you'll have multiple versions to go through.
Regards,
Raphaël Lalonde Lefebvre