diff --git a/lib/gpt_agent.ex b/lib/gpt_agent.ex
index 9c67d3f..79c3915 100644
--- a/lib/gpt_agent.ex
+++ b/lib/gpt_agent.ex
@@ -458,7 +458,7 @@ defmodule GptAgent do
 
       case Registry.lookup(GptAgent.Registry, opts.thread_id) do
         [{pid, :gpt_agent}] ->
-          handle_existing_agent(pid, opts.last_message_id)
+          handle_existing_agent(pid, opts.last_message_id, opts.assistant_id)
 
         [] ->
           handle_no_existing_agent(
@@ -523,10 +523,11 @@ defmodule GptAgent do
 
     defp maybe_subscribe(result, _opts), do: result
 
-    defp handle_existing_agent(pid, last_message_id) do
+    defp handle_existing_agent(pid, last_message_id, assistant_id) do
       log("Found existing GPT Agent with PID #{inspect(pid)}")
       log("Updating last message ID to #{inspect(last_message_id)}")
       GenServer.cast(pid, {:set_last_message_id, last_message_id})
+      GenServer.cast(pid, {:set_assistant_id, assistant_id})
       {:ok, pid}
     end
 
diff --git a/mix.exs b/mix.exs
index ce31dc2..4d2a7ae 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule GptAgent.MixProject do
   def project do
     [
       app: :gpt_agent,
-      version: "6.2.0",
+      version: "7.0.0",
       elixir: "~> 1.16",
       start_permanent: Mix.env() == :prod,
       aliases: aliases(),
diff --git a/test/gpt_agent_test.exs b/test/gpt_agent_test.exs
index aaf11c6..316849d 100644
--- a/test/gpt_agent_test.exs
+++ b/test/gpt_agent_test.exs
@@ -281,16 +281,22 @@ defmodule GptAgentTest do
       refute_receive {^pid, %UserMessageAdded{}}
     end
 
-    test "does not update the assistant id on an agent if the agent is already running",
+    test "updates the assistant id on an agent if the agent is already running",
          %{thread_id: thread_id, assistant_id: assistant_id} do
       {:ok, pid1} =
         GptAgent.connect(thread_id: thread_id, last_message_id: nil, assistant_id: assistant_id)
 
+      new_assistant_id = UUID.uuid4()
+
       {:ok, pid2} =
-        GptAgent.connect(thread_id: thread_id, last_message_id: nil, assistant_id: UUID.uuid4())
+        GptAgent.connect(
+          thread_id: thread_id,
+          last_message_id: nil,
+          assistant_id: new_assistant_id
+        )
 
       assert pid1 == pid2
-      assert %GptAgent{assistant_id: ^assistant_id} = :sys.get_state(pid1)
+      assert %GptAgent{assistant_id: ^new_assistant_id} = :sys.get_state(pid1)
     end
 
     test "loads existing thread run status when connecting to thread with a run history", %{