Example MY transfer function block contains (-kps-ki)/s. Here i need to update the value of kp and ki based on the input(U) to this block. (or) if U < x (some value) need to set kp=0;ki=y else need to set kp=z;ki=0;
The most straightforward method is likely option (3). You can construct the transfer function models via fundamental Simulink blocks with your 'Kp' and 'Ki' values as inputs. You can changes these values according to the necessary logic that you describe above.
My transfer function block is not updating whe i try to change the values , it give sproper result whatsoever . but i am not able to see changes in the block . All it does is converts to num(s)/den(s).