Check any food you have in your bag, and replace any food that is past its expiration date. If you keep your bag in the car most of the time, you may need to switch out your food earlier. Heat makes food age must faster.
If you use external batteries to keep your portable electronics powered up, remember to keep them charged. Over time even if not used, batteries can lose some of their charge.
If you have a generator, be sure to take it out of storage and start it up. Letting your generator run will keep the fluids especially gas in the carburetor to not cause issues. Shut off gas and run it dry when finished.
Make sure that your solar panels are properly working and that you are receiving power through them. Check electrolyte levels of all lead acid batteries. Clean terminals and add protectant.