** LEGAL UPDATE **
Many Liberians who were in the U.S. were granted Temporary Protected Status (TPS) in 1991, as a form of protection from deportation that recognizes that their country had become unsafe to return to. In this case, the grant was due to armed conflict and widespread civil strife.
Following that, in 2007, President Bush approved Liberians who already held TPS for something called Deferred Enforced Departure (DED), a similar status. (The main difference is that a decision to grant DED comes directly from the U.S. president, as a foreign relations consideration, rather than from the U.S. Department of Homeland Security (DHS).)
President Obama extended this grant of DED through March 31, 2018.
Just days from the deadline, however, President Trump has announced that he will end DED for Liberians after one more year--that is, on March 31, 2019.
The stated reason was that "conditions in Liberia have improved" and the country "has made significant progress in restoring stability and democratic governance."
Critics say that, after a quarter century in this country, to ask these people to leave is not only inhumane, but does nothing to advance U.S. interests. A mere 4,000 Liberians is hardly a strain on the U.S. population, and many of them are performing productive work and are well integrated into their communities. (Anyone who is a problem would not have been renewed for DED in the first place.)
If you are a Liberian DED holder, in order to remain through that final 2019 expiration date, you will need to have maintained your eligibility for DED, for example by not having been convicted of an aggravated felony, done anything to convince the U.S. government that your presence or activities in the U.S. have potentially serious adverse foreign policy consequences, or voluntarily returned to Liberia or the last country where you lived.
If you have a work permit (employment authorization document or EAD) with an expiration date of March 31, 2018, you will need to take steps to extend it. U.S. Citizenship and Immigration Services (USCIS) will automatically extend it through September 30, 2018, but that's meant to give you time to submit an application for employment authorization the covers the remaining six months, as well.
To renew your EAD, file an Application for Employment Authorization (Form I-765) with USCIS. The agency began accepting these on March 30, 2018. It's unclear when it will stop accepting them; it asks people to file "as soon as possible."
On Question 16, you must enter (a)(11). Also send a copy of your last Notice of Action (Form I-797) showing your TPS approval as of September 30, 2007, if you have it.
You will need to show some sort of evidence that you've had TPS and continued to have it through March 31, 2018. You'll also need to pay a fee or apply for a fee waiver, either by completing a Request for Fee Waiver on Form I-912 or submitting a personal letter, and providing satisfactory supporting documentation.
USCIS might later call you in for fingerprinting/biometrics.