If you don’t know how is it possible to grind credits/exp after beaten the beasts then this short guide is for you.
Guide to Grinding
You can grind by teleporting back to an area where was enemy you killed before.
Important note: to make them spawn you need to have a “loading” between the teleport otherwise they will not respawn.
It also helps to try to get the upgraded versions of the chips. Especially the damage chips if you have been collecting the materials to make them. Same goes for crafting/buying weapons.