diff --git a/src/claude_monitor/core/settings.py b/src/claude_monitor/core/settings.py
index 14aec1b..3aa1105 100644
--- a/src/claude_monitor/core/settings.py
+++ b/src/claude_monitor/core/settings.py
@@ -269,31 +269,51 @@ def load_with_last_used(cls, argv: Optional[List[str]] = None) -> "Settings":
 
         clear_config = argv and "--clear" in argv
 
+        # Parse CLI arguments manually
+        cli_args = {}
+        cli_provided_fields = set()
+        if argv:
+            i = 0
+            while i < len(argv):
+                arg = argv[i]
+                if arg.startswith("--"):
+                    field_name = arg[2:].replace("-", "_")
+                    if field_name in cls.model_fields:
+                        cli_provided_fields.add(field_name)
+                        # Check if this is a boolean flag or requires a value
+                        if i + 1 < len(argv) and not argv[i + 1].startswith("--"):
+                            # Has a value
+                            cli_args[field_name] = argv[i + 1]
+                            i += 2
+                        else:
+                            # Boolean flag
+                            cli_args[field_name] = True
+                            i += 1
+                    else:
+                        i += 1
+                else:
+                    i += 1
+
         if clear_config:
             last_used = LastUsedParams()
             last_used.clear()
-            settings = cls(_cli_parse_args=argv)
+            settings = cls(**cli_args)
         else:
             last_used = LastUsedParams()
             last_params = last_used.load()
 
-            settings = cls(_cli_parse_args=argv)
-
-            cli_provided_fields = set()
-            if argv:
-                for _i, arg in enumerate(argv):
-                    if arg.startswith("--"):
-                        field_name = arg[2:].replace("-", "_")
-                        if field_name in cls.model_fields:
-                            cli_provided_fields.add(field_name)
-
+            # Merge last_params with cli_args, CLI args take precedence
+            merged_args = {}
             for key, value in last_params.items():
                 if key == "plan":
                     continue
-                if not hasattr(settings, key):
-                    continue
                 if key not in cli_provided_fields:
-                    setattr(settings, key, value)
+                    merged_args[key] = value
+
+            # Add CLI args (they override last_params)
+            merged_args.update(cli_args)
+
+            settings = cls(**merged_args)
 
             if (
                 "plan" in cli_provided_fields
diff --git a/src/tests/test_settings.py b/src/tests/test_settings.py
index af6d534..b0fad88 100644
--- a/src/tests/test_settings.py
+++ b/src/tests/test_settings.py
@@ -573,6 +573,25 @@ def test_load_with_last_used_custom_plan_reset(
             assert settings.plan == "custom"
             assert settings.custom_limit_tokens is None  # Should be reset
 
+    @patch("claude_monitor.core.settings.Settings._get_system_time_format")
+    @patch("claude_monitor.core.settings.Settings._get_system_timezone")
+    def test_load_with_last_used_plan_parsing(
+        self, mock_timezone: Mock, mock_time_format: Mock
+    ) -> None:
+        """Test plan parameter is correctly parsed from CLI arguments."""
+        mock_timezone.return_value = "UTC"
+        mock_time_format.return_value = "24h"
+
+        with patch("claude_monitor.core.settings.LastUsedParams") as MockLastUsed:
+            mock_instance = Mock()
+            mock_instance.load.return_value = {}
+            MockLastUsed.return_value = mock_instance
+
+            # Test various plan values
+            for plan in ["pro", "max5", "max20"]:
+                settings = Settings.load_with_last_used(["--plan", plan])
+                assert settings.plan == plan
+
     def test_to_namespace(self) -> None:
         """Test conversion to argparse.Namespace."""
         settings = Settings(