I think a resistor in series with the RLO pin would create the needed voltage drop so that the ref voltage of the last comparator increases.
The internal resistance is 10K so a 2k resistor should do what you want since the ref is 3.9v and (2k/(10k+2k)) * 3.9v = 0.65v
---------- Post added at 03:32 ---------- Previous post was at 03:24 ----------
My calculation was wrong becasue the last 1K (internal) resistor is before the comparator input so you need less than 1K on RLO pin.
I think a 820 ohm should do the job.