I owe 2700$ for my fed return. Agreed for 700$ by 4/7/19,rest monthly payment and it got approved. Now I don't think I'll be able to pay 700$ by 7th. What to do?

[KittyM]

You can file a revised Application for an installment agreement.  Generally, if you propose to pay off the amount within a year, the IRS will approve your application.  

Here is the IRS web page to Apply For or Revise Your Payment Plan