isnt there a multiplyer for it in the gmapley.constants file based on the difficulty you set? i take a look and see if i can find what your looking for.

ok i checked some files but it seems i was wrong, any how if you want to increase the rate of income it'll have to be for everyone not just the ai.

or look for these lines in your gameplay.constant file:

playerAISharedDef
  table-Aggressive
   BuildShip 10
   BuildModuleTactical 2
   BuildModuleCivilian 1
   BuildModuleResearch 1
   UpgradeResearch 2
   UpgradePlanetArtifactLevel 1
   UpgradePlanetPopulation 1
   UpgradePlanetInfastructure 1
   MaxBountyBidCount 5
  table-Defensive
   BuildShip 5
   BuildModuleTactical 5
   BuildModuleCivilian 1
   BuildModuleResearch 1
   UpgradeResearch 2
   UpgradePlanetArtifactLevel 1
   UpgradePlanetPopulation 1
   UpgradePlanetInfastructure 3
   MaxBountyBidCount 5
  table-Research
   BuildShip 5
   BuildModuleTactical 2
   BuildModuleCivilian 2
   BuildModuleResearch 2
   UpgradeResearch 5
   UpgradePlanetArtifactLevel 2
   UpgradePlanetPopulation 1
   UpgradePlanetInfastructure 2
   MaxBountyBidCount 10
  table-Economic
   BuildShip 5
   BuildModuleTactical 2
   BuildModuleCivilian 5
   BuildModuleResearch 1
   UpgradeResearch 2
   UpgradePlanetArtifactLevel 2
   UpgradePlanetPopulation 5
   UpgradePlanetInfastructure 2
   MaxBountyBidCount 15

the higher the numder after each line the more important (atleast i think so since agressive shipbuild is set to 10 which spawns more ships). and if you want them to run away les often go into the gameplay.constant file in ENTRENCHMENT (since there is no line in vanilla that i saw) and set "aiRetreatThreshold" to .xx (.25 being 25% decrease to lower retreat chance)

here try this and see how it works for you:

table-Aggressive
   BuildShip 10
   BuildModuleTactical 2
   BuildModuleCivilian 6
   BuildModuleResearch 5
   UpgradeResearch 6
   UpgradePlanetArtifactLevel 1
   UpgradePlanetPopulation 5
   UpgradePlanetInfastructure 3
   MaxBountyBidCount 3

i dont know how much good that will do but it might help (i dont know if by increasing the civie build count if it will just spam those antenna things or trade/refinerys)