I reuse my yeast, but not over three times. In this new all grain batch, I pitched at least a cup of WLP001 slurry from a previous IPA ² batch that had an OG 1.096 and FG of 1.013. This new batch is a Rye PA ² with an OG of 1.091. I used O2 right after cooling the wort and yeast nutrient in the last 10 minutes of the boil. This yeast has slowed way down. I brewed last Saturday, so it's been 6 days of primary...but it's only gotten to 1.038, and I want it down to at least 1.018. The temperature has been between 65 and 70 degrees farenheit and I rouse the yeast at least twice a day. There's still an inch of krausen, so I'm just not sure what's going on. I'm thinking the sluggishness is because of the great performance that the yeast had done for that last batch. I can make a new starter and use my stir plate, then step it up and pitch it into this batch. Or I can can brew a 1.060 to 1.070 IPA as a propegation batch and rack this slowly fermenting batch onto a fresh yeast cake in a week. Any suggestions would be greatly appreciated.