IF the document is submitted into the LHDN, and need to retrieve back the document :
1. KEYIN new document with same DOCUMENT NUMBER, same DOCUMENT DATA/INFO. 
2. Click SAVE 
3. Go to MORE (left side of the document) 
4. Click on SEARCH ICON 

5. Search the date and click APPLY 
6. Choose the RELATED document.
7. Click UPDATE

//may refer to the image below