diff --git a/python/langsmith/evaluation/_arunner.py b/python/langsmith/evaluation/_arunner.py
index a8799b083..073014970 100644
--- a/python/langsmith/evaluation/_arunner.py
+++ b/python/langsmith/evaluation/_arunner.py
@@ -843,8 +843,12 @@ async def _aend(self) -> None:
         project_metadata["dataset_splits"] = await self._get_dataset_splits()
         self.client.update_project(
             experiment.id,
-            end_time=datetime.datetime.now(datetime.timezone.utc),
-            metadata=project_metadata,
+            end_time=experiment.end_time
+            or datetime.datetime.now(datetime.timezone.utc),
+            metadata={
+                **experiment.metadata,
+                **project_metadata,
+            },
         )
 
 
diff --git a/python/langsmith/evaluation/_runner.py b/python/langsmith/evaluation/_runner.py
index 2339601c6..f4e2076ec 100644
--- a/python/langsmith/evaluation/_runner.py
+++ b/python/langsmith/evaluation/_runner.py
@@ -1587,8 +1587,12 @@ def _end(self) -> None:
         project_metadata["dataset_splits"] = self._get_dataset_splits()
         self.client.update_project(
             experiment.id,
-            end_time=datetime.datetime.now(datetime.timezone.utc),
-            metadata=project_metadata,
+            end_time=experiment.end_time
+            or datetime.datetime.now(datetime.timezone.utc),
+            metadata={
+                **experiment.metadata,
+                **project_metadata,
+            },
         )
 
 
diff --git a/python/pyproject.toml b/python/pyproject.toml
index d6425e255..12e89ba74 100644
--- a/python/pyproject.toml
+++ b/python/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "langsmith"
-version = "0.1.144"
+version = "0.1.145"
 description = "Client library to connect to the LangSmith LLM Tracing and Evaluation Platform."
 authors = ["LangChain <support@langchain.dev>"]
 license = "MIT"