In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?
When you adjust a constant speed propeller to a higher rpm, this will be done by making the propeller blade AoA smaller.
Contrary to your question though, manifold pressure and power output will not remain constant unless you adjust the throttle. Neither will your airspeed, not surprisingly.
Exact effect will depend on the engine, but basically power is torque x rpm, so for a constant throttle position, increase in rpm will increase power output unless we are near max rpm.
See What is the relation between manifold pressure, RPM, and power, in a constant speed prop? for reference.