The very latest versions of TomTom will accept what is known as a 'gpx' file for routing purposes. You can create such routes with a variety of online tools and locally based apps.
These newer units also accept traditional TomTom itinerary ('itn') files. Loading them to the new units requires only that you have the device plugged into a PC and that you can upload your route to a web page at TomTom. The itinerary (or route, above) is then transferred to your device in a form that it recognizes.
Unlike your 720, which could have the files either dropped directly into its directory structure in the right spot, or by using Home, newer units use a web page at TomTom to accomplish that kind of job.
So should your unit die on the road, you would want to be SURE that you had the route stored on your tablet, and that your tablet interacts correctly with the web page at TomTom using whatever browser it uses.
Of course, and perhaps even more important, you would need to get your new unit working properly with your tablet, too. Not knowing what you have, it's hard to know if it would support the app that now connects TomTom units to computers. Let us know specifically what OS your tablet is running. If you have a Windows or iOS based tablet, it should work. Try downloading the new MyDrive app that more or less replaces Home onto your tablet (see here >>>
https://www.tomtom.com/en_gb/mytomtom/getstarted/deviceselector.jsp ) and grab whichever of the two is right for your tablet. If it runs, you're probably going to be good to go.