Hand Bumper STEP Adjustment

I already have a fully modelled STEP file for a hand-protector bumper that covers the knuckles, four fingers and thumb. All I need is a simple dimensional tweak: every feature that sits above the base plane must be raised uniformly by exactly 1.5 mm... (Budget: $10 - $30 USD, Jobs: 3D CAD, 3D Design, 3D Modelling, 3D Rendering, AutoCAD, CAD / SolidWorks, CAD/CAM, Solidworks)