Can I get the back of my tablety replaced?

Your best and most cost effective way to prevent damage is to have a professional do it. That being said you can visit www.fruitfixed.com for a number to call to obtain a quote. So otherwise your options are to find a broke one say on eBay that is damaged in another way besides the backing. Make a fair offer or buy it now if it's reasonable and swap the casing off the broke other with your broke backing.