deck products offer a decent working life, regardless of warranty periods. One year is quite common. I’ve been monitoring deck finishes for about 20 years, and the best performance I’ve seen for a tinted transparent finish is 3 years in direct sunlight. Opaque finishes might last a year or two more.

The main challenge you face right now is preparation, and this means sanding. You can use a vibrating plate sander on the flat areas of your deck, and a hand-held random orbit sander to get into smaller areas. Use an 80-grit abrasive on both machines. There’s more to deck preparation and finishing techniques than I have room to describe here, but you can download a free copy of my deck finishing report.