Does resistance decrease over a resistor?
Resistivity is a physical property of material and it will not adjust itself to satisfy Ohm's law.
So, the value of a resistor or resistance itself has nothing to do with Ohm's law. 

Resistance can be expressed by
$$ R = \rho \frac{\ell}{A}$$
where 
\$ \ell \$ is the length of the resistor, A is the cross-sectional area of the resistor (in m²) and ρ is the electrical resistivity (also called specific electrical resistance) of the material.

Depending of the point of view, the resistance decreases (or increases) with length.