Re-Applying Stain After A Year (Plus Lattice)

Last year in July I followed the advice I found on this site to clean and stain my deck. I used Restore-a-Deck cleaner/brightener with Defy Extreme stain and it worked quite well for the most part.

I have a 400 sq-ft PT Pine deck in full sun. I bought a 5-gallon container of Defy Extreme and it was just barely enough to cover the deck and stairs (mostly). I never ended up getting to some of the side panels and the lattice.

I have a few questions about what to do now:

1. Since my deck needed the stain so badly, I needed to use a lot of stain and as I mentioned I didn't have quite enough to go around. This also led to me being a bit stingy with parts of deck flooring. I believe I may not have put quite enough on in general (it's more noticeable in a few spots). Some parts of railings bead rain water, but on some parts of the deck it still soaks in. I did do 2 coats wet-on-wet, but I was moving rather quickly and realized in process that I was going to run out of stain since I did the floor/stairs last.

Can I re-apply more stain on the deck floor almost a year later in order to improve the coverage/protection or to touch up spots that may look a little uneven? If not, do I need to fully clean/brighten again to re-apply, or can I do a very basic clean to prepare the wood? My deck has no apparent mold/mildew issues and is generally clean.

2. What's the best way to do the lattice? I have a lot of lattice around my deck, some sections with doors built in to access underneath. Should I clean/brighten the lattice and apply the stain by hand? This would be extremely tedious and time-consuming, but I'd like to match the lattice with the deck and protect it if possible.

I've seen aerosol can stain sprayers that looked convenient. Are there any other alternatives besides replacing with new lattice? It's in fairly good condition, but just quite faded and grey.

Also, I'm trying to decide if I should buy another 5-gallon container of Defy Extreme so I can be sure I have enough. If I can re-apply or touch up every year or 2 I would definitely buy a 5-gallon. Once the container is opened, will it last a long time as long as I keep it sealed?

I apologize for the wall of text, but hopefully someone can help me!

TL;DR - can I re-apply Defy Extreme stain nearly a year later in order to improve coverage or touch up sections? Also, what's the best way to do lattice?

Thanks,

Evan