diff --git a/jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.js b/jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.js
index 2e71e6b..44741f2 100644
--- a/jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.js
+++ b/jey_erp/jey_erp/doctype/bank_statement_importer/bank_statement_importer.js
@@ -189,14 +189,24 @@ const BIFileFormat = {
 		});
 	},
 
-	// Called when the user attaches / replaces the Sample Excel File. Refresh
-	// the Excel Column dropdown and, if the table is still empty, run
-	// auto-detect silently. We never overwrite a user-filled table.
+	// Called when the user attaches / replaces / clears the Sample Excel File.
+	// Refresh the Excel Column dropdown, then either auto-detect silently
+	// (empty table) or ask before overwriting an existing mapping (re-upload).
 	onSampleFileChange(frm) {
 		this.applySampleHeaders(frm, /*force*/ true);
+		if (!frm.doc.sample_file) return;
+
 		const hasRows = (frm.doc.column_mappings || []).some(r => r.excel_column || r.standard_field);
-		if (!frm.doc.sample_file || hasRows) return;
-		this.autoDetect(frm, /*silent*/ true);
+		if (!hasRows) {
+			this.autoDetect(frm, /*silent*/ true);
+			return;
+		}
+		frappe.confirm(
+			__('Re-run auto-detect and replace the existing {0} Column Mapping row(s)?', [
+				frm.doc.column_mappings.length,
+			]),
+			() => this.autoDetect(frm, /*silent*/ true),
+		);
 	},
 
 	setColumnOptions(frm, headers) {