The answer is yes ... but no.
Yes in that you can upgrade your iOS without losing all your data and settings and such. You can upgrade using the over-the-air (OTA) updates from Apple or by connecting the iPad to iTunes and selecting the Upgrade button.it is relatively,straightforward, although making a backup before upgrading is always a good idea (and thus always recommended).
The answer is "no" in that you can no longer upgrade to iOS 5.x. The only available iOS is the current one - iOS 6.1.3. You can't selectively upgrade to any other iOS. Sorry.
Hope this clarifies.
Marilyn