diff --git a/completion.py b/completion.py
index e8484e34e..9cbb21392 100644
--- a/completion.py
+++ b/completion.py
@@ -23,14 +23,20 @@ def get_completion(clones_dir: str, repo: str) -> tuple[float, str, float]:
     clone_path = Path(clones_dir, 'translations', repo)
     for branch in branches_from_peps() + ['master', 'main']:
         try:
-            clone_repo = git.Repo.clone_from(
-                f'https://github.com/{repo}.git', clone_path, branch=branch
-            )
+            if not clone_path.exists():
+                clone_repo = git.Repo.clone_from(
+                    f'https://github.com/{repo}.git', clone_path, branch=branch
+                )
+            else:
+                (clone_repo := git.Repo(clone_path)).git.fetch()
+                clone_repo.git.switch(branch)
+                clone_repo.git.pull()
         except git.GitCommandError:
-            print(f'failed to clone {repo} {branch}')
+            print(f'failure: {branch} {repo}: clone or switch, continuing')
             branch = ''
             continue
         else:
+            print(f'success: {branch} {repo}: clone or switch')
             break
     path_for_merge = Path(clones_dir, 'rebased_translations', repo)
     completion = potodo.merge_and_scan_paths(
diff --git a/generate.py b/generate.py
index 2a8292b56..88d05e8ad 100644
--- a/generate.py
+++ b/generate.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import json
 import concurrent.futures
 import itertools
@@ -20,20 +22,26 @@
 generation_time = datetime.now(timezone.utc)
 
 
-def get_completion_progress() -> Iterator['LanguageProjectData']:
+def get_completion_progress() -> Iterator[LanguageProjectData]:
     clones_dir = Path('clones')
-    Repo.clone_from(
-        'https://github.com/python/devguide.git',
-        devguide_dir := Path(clones_dir, 'devguide'),
-        depth=1,
-    )
+    if not (devguide_dir := Path(clones_dir, 'devguide')).exists():
+        Repo.clone_from('https://github.com/python/devguide.git', devguide_dir, depth=1)
+    else:
+        Repo(devguide_dir).git.pull()
     latest_branch = branches_from_peps()[0]
-    Repo.clone_from(
-        'https://github.com/python/cpython.git',
-        cpython_dir := Path(clones_dir, 'cpython'),
-        depth=1,
-        branch=latest_branch,
-    )
+    if not (cpython_dir := Path(clones_dir, 'cpython')).exists():
+        Repo.clone_from(
+            'https://github.com/python/cpython.git',
+            cpython_dir,
+            depth=1,
+            branch=latest_branch,
+        )
+    else:
+        (cpython_repo := Repo(cpython_dir)).git.fetch()
+        cpython_repo.git.switch(latest_branch)
+        cpython_repo.git.pull()
+
+    subprocess.run(['make', '-C', cpython_dir / 'Doc', 'clean'], check=True)
     subprocess.run(['make', '-C', cpython_dir / 'Doc', 'venv'], check=True)
     subprocess.run(['make', '-C', cpython_dir / 'Doc', 'gettext'], check=True)
 
@@ -56,7 +64,7 @@ def get_project_data(
     repo: str | None,
     languages_built: dict[str, str],
     clones_dir: str,
-) -> 'LanguageProjectData':
+) -> LanguageProjectData:
     built = language.code in languages_built
     if repo:
         completion, branch, change = get_completion(clones_dir, repo)