add persist_for to pru

Change-Id: I3ec0601ed6a281cdbabb0639ecbffc3fd69d0990

pru.view.lkml

diff --git a/pru.view.lkml b/pru.view.lkml
index 6e676f6..a2643d6 100644
--- a/pru.view.lkml
+++ b/pru.view.lkml
@@ -2,6 +2,7 @@
 
 view: pru {
   derived_table : {
+    persist_for: "24 hours"
     explore_source: uli_view {
       column: partition_date {
         field: uli_view.partition_date