The scholarly base has to be maintained or it will wither away. How can you maintain your scholarly base?
*Do research. If you are always reading and writing, then the scholarly base will be constantly renewed.
*Teach new texts, new areas of investigation. I often times teach areas where I'm not the expert (yet). This forces me to learn new things. For undergraduates, it doesn't really matter whether you are a world-class expert in the material.
*Read outside your field and discipline. I was talking to someone in another department the other day, and he said "How come you know so much about X?" I don't a thing about it, really, but I knew enough to have an intelligent conversation about his area of specialization, which has nothing to do with my own. It's not even the same "school" in the university.
*Follow the "arts." Music, art, painting, cinema, architecture. If those aren't your primary field, you should still study them, because they provide different ways of thinking.
*Stretch your brain in other ways. Study a language you don't know quite as well.
*Talk to smart, interesting people. You get dumber when around dumb people and rise to a different level around smart people.
*Spend time just maintaining and expanding the base. Don't feel every minute of "research" has to be purposeful.
*Re-evaluate the base at significant junctures: after the PhD defense, after getting tenure or a new job.
*Help others develop their scholarly bases. Spread the wealth around, because it won't make you any poorer.