is a proton pump
inhibitor, reduces acid secretion in stomach, so that there is less acid reflux
Its not that the tablet has stopped working but may be the condition has worsened because of change in habits like lying down on bed immediately after taking lunch or dinner, late night meals etc.
Do regular scopy to note any cancerous change in oesophagus that may occur due to chronic irritation by acid reflux.
Consider operative intervention with ur Surgeon's opinion.