How do I ensure I don't need to do another reinstall

I recently experienced a bug on DI 3.0 where my sparks went to a negative figure and collecting new sparks makes no change to the spark count. More details can be found at viewtopic.php?f=45&t=14045

I've contacted Support and they are not able to help me. It seems my only option is to do a reinstall

Any suggestions on how I can avoid this happening again? For example is it possible to make backups of my save files on a USB stick, so that if I ever get hit by this negative sparks bug again, I can revert to an old save file?

Don't know about USB/save files - seems like Disney Infinity is designed as a "black box" - with various saves of Play Sets, Toy Boxes, & overall progress meant to be handled within the game itself. Really don't know though.

Farming had some issues for some fans months back, and if farming brought you the spark bug, I'd avoid farming .

After the reinstall, make that spark generator & unlock everything from the Toy Store that you can without needing separate missions/feats from Play Sets & Expansion Games. Then if you hit negative again, at least you have the toys, and a choice.

I can't speak for the ps4, but on wiiu it is possible to copy the save files to an external hard drive or usb drive. This is a good reminder to me to make a new backup myself.

I believe you can use the Playstation's save cloud feature as well, so you can restore the game to an earlier point where it was working normally.