Brett Brux: Repitch or buy new

I'm getting ready to brew another "lambic" I've brewed twice. The first batch came out 1.002, the second batch was pitched on the yeast cake of the first and came out 1.008. Should I pull some of the yeast cake for a starter or buy a new Brett Brux vial and start fresh? The second batch just went on fruit and I was going to brew Saturday or Sunday this week and age it another year, or until it hits FG.

I am not clear what you are asking. Does the yeast cake from batch #2 already have the Brett Brux in it, and you are looking to make a third batch?

What yeast did you use for your primary fermentation for batch #1?

I would be inclined to start fresh with a Sacch yeast and then add some dregs from batch #2 for secondary but it depends on what you are going for. Repeatedly pitching on the cake from the original batch #1 may eventually change the balance of the yeasts, but that may be a good thing.

100% Bret brux. No yeast added. Seeing if people think I should buy a fresh pitch or pitch on the yeast cake from batch 2. I bought new Brett.

So both the existing cake and the new vial are 100% Bret brux? I don't think it matters what you pitch.

I think the OP is noticing that his attenuation is changing after reusing the yeast and wondering if he should not reuse in order to get the original attenuation.

I don't think that your strain would have mutated that much yet and would look to other causes for the under attenuation. Same recipe/ingredient source? Mash or fermentation temperature? I am guessing fermentation temperature based on the weather and location, but just a guess.

@MrFancyPlants yeah same recipe. Unsure of mash temp but I'd say so. I'll give it one last try and see how it goes. Hopefully I'll have some extra wort I can use for a starter.