you should either create a mockup of the SQLitePlugin that fakes a database (by using a python dictionary), or create and destroy a SQLite database (with a dataset matching your tests) before and after each set of tests.
basically, you could do something like:
import webtest
def test_home():
plugin = bottle_sqlite.SQLitePlugin(dbfile='my_test_data_set.db')
example.app.install(plugin)
app = webtest.TestApp(example.app)
assert app.get('/').status == '200 OK'
example.app.uninstall(plugin)
or
import webtest
def test_home():
plugin = bottle_sqlite.SQLitePluginMockup(dataset)
example.app.install(plugin)
app = webtest.TestApp(example.app)
assert app.get('/').status == '200 OK'
example.app.uninstall(plugin)
where dataset would be a "hand made" dictionary faking the dataset for your application.
Or you may be able to do it once and for all in global context of your test script.
HTH