In the situation where you've already submitted your proposal and the closing date is extended, you are not required to re-submit your bid. 

NOTE: It is still recommended that you find out why the project was extended and if there are any changes or addenda to be aware of that may affect your proposal. Often times a Project Owner will post a Public Notice with additional details, where you can check how to view this from our viewing a Public Notice page.

If you are looking to un-submit and modify your submission, you can do so up until the new close date of the opportunity. (See our Can I revise my submission? page.)