All 12 Scottish Premier League clubs will meet at Hampden to vote on the proposals which includes a move to a 12-12-18 league structure - with it then splitting into 8-8-8-18 after 22 games - the move to a single league and a redistribution of monies.
It requires an 11-1 vote to progress but St Mirren chairman Stewart Gilmour has indicated that the Buddies will vote against the proposal vote, while he is also against the continuation of the 11-1 which is required for certain issues.
There remains uncertainty about Ross County's position but Lawwell told Celtic's official website: "We are coming to the end of the process and it's either change or the status quo.
"When you look across over the wall, if it doesn't happen, then what is the flip side? And the flip side is it stays the same. That, to me, is not palatable.
"From Celtic's point of view, come Monday night if it doesn't go through, we'll be disappointed because we put a lot of work into it and we see it as the right thing for the game.
"It would be unfortunate for the longer term interests of the whole game in Scotland as it would be a huge opportunity lost."
Lawwell claimed the changes will lead to, among other things, more meaningful fixtures and stability within the game.
"Firstly, we are very, very close," he said.
"And we felt it was unanimous, up until recently, that this should be taken forward.
"The second reason is because we think it is right for the game. It's not perfect but it's the best available. The reason we think that is because it gives the one body which is a positive.
"It gives redistribution to the SFL which actually transforms, financially, the majority of the SFL clubs.
"And it also provides more meaningful games and that I think we can see even in the last week.
"The last three times we went to St Mirren there were 6,000 there. Nine thousand were at the Ramsdens Cup final, so too at Partick Thistle against Morton, and St Mirren also took about 17,000 to Hampden (for the Scottish Communities League Cup final).
"When there is something to play for, when there are meaningful games, the fans come out.
"It will give more meaningful games and therefore more attraction to the fans. Therefore, more attraction to broadcasters and therefore more attraction to sponsors.
"It will also give us stability. We've been at this for three years and we've never come as close to an agreement. I think stability is vital. If we get two or three years' stability it gives the league credibility and something back to our broadcasters and sponsors.
"In football, stability is everything."
Lawwell revealed his disappointment with regards St Mirren's position but is hopeful all other clubs can work together to take the game forward.
"We're disappointed there appears to be some positions changed in recent weeks but we respect the right of every club to have their own vote," he said.
"We believe in the voting structure for the protected items because these are huge decisions with huge implications.
"We respect the fact they have to do what is right for them but we have to take into account what is right for Scottish football. We respect the right but we need to understand the reasons for clubs would want to vote against this."