[…] Your praise shall still find room (10)
The purpose of this poem is to praise the beloved. At first you're probably like, "Dude, where's the praise?", because there isn't a lot of obvious complimenting. But this is one of those sneaky poems that tells you all along what it's going to do, and while you wait for it to finally get up and at it, you realize that it's been doing it all along. Sonnet 55 claims it's going to praise the beloved, and guess what? It's sneakily doing it in every line. Sometimes it's obvious, like in line 3; most of the time it's under the radar, implied in every image of war or destruction or death that ruins the world but spares this one beloved boy.
Even in the eyes of all posterity (11)
And it's not just the speaker who's filled up to the brim with praise. The whole world is full of love for this nameless man, thanks to these sonnets that praise him eternally.
You live in this, and dwell in lovers' eyes (14)
The plural "lovers" reemphasizes that everyone loves the beloved. Once they meet him in the fourteen lines of this sonnet, his memory will live forever in their eyes, now imprinted with the words that praise him.