How do I refresh my deck without having to sand and stain it all?

You can use a deck cleaner and brightener.

I suggest you use a outdoor paint that matches the color of stain you have currently that's what i did an it came out great!, if you wanted to stain it thats going to require those extra steps of sanding it exc.

Thompsons water seal now makes a paint for older decks with splinters etc. Don't need to wash, it is thick and leaves a nice texture

Do what Janet suggests. The use Thompsons Water Seal to to water proof and UV protect it. Don't use any deck over product like Brenda suggests. They tend to crack and peel after about a year or two.