Please Help - How to use calculated value of a function F at time step 1, for calculation at time step 2 and so on

I want to calculate the value of a function F(T,t)=A(T)*F(T,t).
It means for calculating the F in a time step 2, I need the value of F from previous steps (step1). Can anyone help me to do such calculation in the heat transfer module of COMSOL.

For example : my variable : E_PC (step i) = E_PC (step i-1) - 0.01

For exemple : A = A + 1.5
( circular variable the new A = the previous A + 1.5)

Please what i can do it with comsol 4.3

thank's