diff --git a/gitdriver.py b/gitdriver.py
index 15473ed..2b74d55 100644
--- a/gitdriver.py
+++ b/gitdriver.py
@@ -22,6 +22,28 @@ def parse_args():
 
     return p.parse_args()
 
+def commit_revision(gd, opts, rev):
+    with open('content', 'w') as fd:
+        if 'exportLinks' in rev and not opts.raw:
+            # If the file provides an 'exportLinks' dictionary,
+            # download the requested MIME type.
+            r = gd.session.get(rev['exportLinks'][opts.mime_type])
+        elif 'downloadUrl' in rev:
+            # Otherwise, if there is a downloadUrl, use that.
+            r = gd.session.get(rev['downloadUrl'])
+        else:
+            raise KeyError('unable to download revision')
+
+        # Write file content into local file.
+        for chunk in r.iter_content():
+            fd.write(chunk)
+
+    # Commit changes to repository.
+    subprocess.call(['git', 'add', 'content'])
+    subprocess.call(['git', 'commit', '-m',
+        'revision from %s' % rev['modifiedDate']])
+
+
 def main():
     opts = parse_args()
     if not opts.mime_type:
@@ -41,33 +63,30 @@ def main():
     # an exception if the file does not exist.
     md = gd.get_file_metadata(opts.docid)
 
-    # Initialize the git repository.
-    print 'Create repository "%(title)s"' % md
-    subprocess.call(['git','init',md['title']])
-    os.chdir(md['title'])
-
-    # Iterate over the revisions (from oldest to newest).
-    for rev in gd.revisions(opts.docid):
-        with open('content', 'w') as fd:
-            if 'exportLinks' in rev and not opts.raw:
-                # If the file provides an 'exportLinks' dictionary,
-                # download the requested MIME type.
-                r = gd.session.get(rev['exportLinks'][opts.mime_type])
-            elif 'downloadUrl' in rev:
-                # Otherwise, if there is a downloadUrl, use that.
-                r = gd.session.get(rev['downloadUrl'])
-            else:
-                raise KeyError('unable to download revision')
-
-            # Write file content into local file.
-            for chunk in r.iter_content():
-                fd.write(chunk)
-
-        # Commit changes to repository.
-        subprocess.call(['git', 'add', 'content'])
-        subprocess.call(['git', 'commit', '-m',
-            'revision from %s' % rev['modifiedDate']])
+    if os.path.isdir(md['title']):
+        # Find revision matching last commit and process only following revisions
+        os.chdir(md['title'])
+        print 'Update repository "%(title)s"' % md
+        last_commit_message = subprocess.check_output('git log -n 1 --format=%B', shell=True)
+        print 'Last commit: ' + last_commit_message + 'Iterating Google Drive revisions:'
+        revision_matched = False
+        for rev in gd.revisions(opts.docid):            
+            if revision_matched:
+                print "New revision: " + rev['modifiedDate']
+                commit_revision(gd, opts, rev)
+            if rev['modifiedDate'] in last_commit_message:
+                print "Found matching revision: " + rev['modifiedDate']
+                revision_matched = True
+        print "Repository is up to date."
+    else:
+        # Initialize the git repository.
+        print 'Create repository "%(title)s"' % md
+        subprocess.call(['git','init',md['title']])
+        os.chdir(md['title'])
 
+        # Iterate over the revisions (from oldest to newest).
+        for rev in gd.revisions(opts.docid):
+            commit_revision(gd, opts, rev)
 if __name__ == '__main__':
     main()