Don't know the system you refer to or AC type??
However, 23 flex 35C is NOT THE SAME as 25 flex 35C.
1) In order to find the N1 value appropriate to the flex temp you need to correct for the difference between the OAT and the Flex temp. If the OAT has changed the N1 is no longer valid.
2) Lift depends on rho. rho changes with temperature.