It really depends on the quality and condition of the cabinet boxes themselves and what you want to do. If they are decent cabinets and you just want to change color, you can just paint them if they are in good condition. The lifespan of painting depends a lot on the quality of the paint job.
If you want something more choices, like a wood grain, that can be achieved too through refacing. I would only recommend this if you have good cabinet boxes underneath. Wood cabinets from a custom shop or high end production cabinets would be worth keeping. You can order veneers that can be adhered to the frames and sides and doors, drawer fronts and drawer boxes can be ordered from a number of online suppliers and the process is not too difficult if you take your time and pay attention to details. The prices range widely depending mostly on what you want.
If it turns out the boxes are cheap production particleboard cabinets, then you would probably be just as well off replacing them especially since you are replacing the top as well.
Hope that helps and good luck with your project!