diff --git a/installers/charm/pla/src/charm.py b/installers/charm/pla/src/charm.py
index 1fc6386..e137394 100755
--- a/installers/charm/pla/src/charm.py
+++ b/installers/charm/pla/src/charm.py
@@ -84,7 +84,7 @@
         config = self.framework.model.config
 
         ports = [
-            {"name": "port", "containerPort": config["port"], "protocol": "TCP", },
+            {"name": "port", "containerPort": config["port"], "protocol": "TCP",},
         ]
 
         config_spec = {
@@ -123,23 +123,23 @@
         """Upgrade the charm."""
         unit = self.model.unit
         unit.status = MaintenanceStatus("Upgrading charm")
-        self.on_start(event)
+        self._apply_spec()
 
     def on_kafka_relation_changed(self, event):
-        unit = self.model.unit
-        if not unit.is_leader():
-            return
-        self.state.kafka_host = event.relation.data[event.unit].get("host")
-        self.state.kafka_port = event.relation.data[event.unit].get("port")
+        kafka_host = event.relation.data[event.unit].get("host")
+        kafka_port = event.relation.data[event.unit].get("port")
+        if kafka_host and self.state.kafka_host != kafka_host:
+            self.state.kafka_host = kafka_host
+        if kafka_port and self.state.kafka_port != kafka_port:
+            self.state.kafka_port = kafka_port
         self._apply_spec()
 
     def on_mongo_relation_changed(self, event):
-        unit = self.model.unit
-        if not unit.is_leader():
-            return
-        self.state.mongodb_uri = event.relation.data[event.unit].get(
+        mongodb_uri = event.relation.data[event.unit].get(
             "connection_string"
         )
+        if mongodb_uri and self.state.mongodb_uri != mongodb_uri:
+            self.state.mongodb_uri = mongodb_uri
         self._apply_spec()