you have a few options both of which require some scripting.
1) You can expose certain variables (input and output) of your model as parameters (right click on them then select "model parameter") , then call that model from a loop in a script.
2) Export your model to a script, and add a loop around your buffer/clip operations.
What you need to get is a list of your inputs. If those are feature classes (in a gdb) or shp files, you can use the GpDispatch.ListFeatureclasses.
Have a look at the Geoprocessing help for more details on this.