Need advice on what to do next with this deck cleaning / stripping / staining

Hello...  I started a deck restaining project but not sure I'm doing it correctly, and I may actually be causing myself more work.  So, I've stopped to get some advice.

Two years ago, I stripped my deck planks by sanding them to bare wood and then stained with semitransparent SW DeckScape.  It looked good, but only two years later I have a few spots chipping / peeling away.  

Since I restored the boards by sanding last time, I thought I'd just strip it down with chemicals this time and redo, but the stain is not coming off easily.  So, I returned to the web to get some online help and now I think that maybe I didn't need to strip it at all. 

** I thought I needed to strip because I put some tape down on those areas where it was chipping and pulled stain off**  

I've completed about 1/10th of the deck.  Should I continue stripping or just clean and restain it as is?  

I intend to recover with DeckScape but a slightly different color (more brown than red).

Here's what it looks like (this is a pic of the 75% of the deck I haven't applied stripper to). I know I went a little too strong with the pressure washer because it's fusing up (I figured I was going to do a light sanding anyway so I didn't think it mattered). 

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 Here's the 25% I stripped:

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I'm using a mixture of Pressure Tek F18 stripper and 10% sodium hypochlorite applied with a pump sprayer.  Let dwell approx 15 - 30 mins and rinse off at approx 1000psi.  I also intend to use F8 Brightener / Neutralizer after my last round of F18.

QUESTIONS:  

1. Should I stop stripping, finish cleaning the deck with SH, than only sand the boards I've already stripped and apply stain to the entire deck?

2. If I continue stripping, do I need to remove ALL the old stain?  I'm reapplying same manufacture product and probably a little darker.  (can I stain over what I've already stripped now, or does more of that old stain need to be removed?)

3. How concerned do I need to be about getting SH on glass? I don't want to etch my glass doors. I rinsed them before and after, but they're not saying wet long enough to prevent the overspray SH from getting on the glass and drying (hand pumping chemicals takes me a long time). 

4. Lastly, if you guys recommend fully striping. What's the easiest way?  I probably spend 30 hours sanding down those deck boards just two years ago.  I'll swap them out with composite boards before working that hard on them again!  I used a belt sander and orbital sander last time.  I saw a product called Diamabrush that looks fast, but expensive and might not be too durable. 

Any advice is GREATLY appreciated.  Thank you!