As you add electrons to an energy level, without adding more protons are there more or less repulsive
forces between the electrons?

There will be more repulsive force between the electrons.

Explanation:

Electrons contain negative charge.As a result the electron will repulse another adjacent negatively charged electron.

   According to the given question addition of electrons to en energy level without adding more protons will increase the overall negative charge in the the energy level in which the electrons are added.

  This ultimately leads to generate more repulsive force between the electrons.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.