It's best to just do it over. Every time you do a fresh run through it, you get loot drops. You can get 310 drops and then you won't be tripping over not completing it last week. The way the Raids are set up are purposely developed for you to keep playing them. You get gear to increase your light level, and even if you get stuff that you already have, you can infuse it into your favorite gear and bump that stuff up.
I got my Black Spindle up to 305 because I got 3 Raid Shotties that I didn't need. You also can get Exotic Engrams from popping 3 of Coins before dropping bosses