Sen. Nelson is determined to seat Florida delegates and is putting together a mail-in vote plan:

Florida Democrats were moving forward Monday with a plan to redo their presidential primary using privately-funded mail-in ballots, a key state party official said, even though some congressional and party leaders had yet to sign on to the idea.
“We’re huddling with state brass now,” the official said. “The spotlight will be on us. We will have a detailed plan.”

The official said the state party expected both the Clinton and Obama campaigns to eventually agree to the plan.
“They’ve seen the writing on the wall and they realize this is something they need to get behind,” the official said. “Both campaigns have reacted favorably to the idea so far.”
Both Florida and Michigan have been studying ways to hold re-votes now that the Democratic contest remains so close and their states could determine the winner. The states’ previous primaries were held earlier in the election season than party rules allowed, prompting the Democratic National Committee not to count their delegates.
The plan would be funded with money raised by the Florida Democratic Party and possibly include the help of the campaigns, the official said. The plan would also provide for the possibility of voting auditors and third parties to provide independent accountability.
The plan could eventually call on the state to play an active role in the mail-in primary, something Sen. Bill Nelson, D-Florida, has been actively pushing.