The Prime Minister has claimed her Withdrawal Agreement will be "new and improved" when it returns to the Commons in June.
MPs will be voting on the Bill for a fourth time the week beginning June 3, but Mrs May promised a "bold new offer" in a column in the Sunday Times.
The weekly meeting of the Cabinet on Tuesday is expected to sign off on a package of measures to be included in the forthcoming Bill, aimed at winning cross-party support.
The talks come amid widespread scepticism that the deal will fare any better than her three previous failed attempts to get the deal through the Commons.
A government source said the Bill - which is needed to ratify the deal with Brussels - would include new measures on protecting workers' rights, an issue where agreement with Labour was said to have been close.
However, the source made clear the package would not just be aimed at Labour MPs but would seek to secure the widest possible support across the Commons.
It is expected to include provisions on future trade arrangements with the EU, on environmental protections, and on Northern Ireland, including the use of technology to avoid the need for border controls with the Republic.
It will not, however, seek to re-open the Withdrawal Agreement - which included the controversial Northern Ireland "backstop" - after the EU repeatedly made clear it could not be re-negotiated.
Regardless of how the vote goes, Mrs May will then meet the chairman of the Tory backbench 1922 Committee, Sir Graham Brady, to agree a timetable to elect her successor as party leader, paving the way for her departure from Number 10.
The Prime Minister expected to set out details of her WAB proposals in a major speech before the end of the month.