When following active surveillance paradigm, what PSA increase will trigger prostate biopsy?   

NCCN states that per an AS paradigm for low risk and FIR prostate cancer, a PSA should not be collected any more than every 6 months, with DRE, mpMRI and prostate biopsy no more than every 12 months. It also states that a repeat prostate biopsy should also be considered if the prostate exam changes, if mpMRI (if done) suggests more aggressive disease, or if PSA increases. 

What level of increase in PSA would you say merits repeat prostate biopsy per AS paradigm? If a patient has a mild increase from a level of 4.2 ng/mL to 4.4 ng/mL after 6 months of AS, would this be enough to prompt a repeat biopsy? Would you obtain a second confirmatory PSA level before biopsy?