Frontier Airlines is making another offer to merge with bankrupt Spirit Airlines, less than two years after a previous plan fell through.

Spirit, which filed for bankruptcy protection last year, says it has rejected the new Frontier overture but would be open to a higher offer.

Spirit Airlines rejected Frontier Airlines' second attempt to merge the two companies on Wednesday and will continue with its plans to exit bankruptcy. Frontier made an offer in early January for Spirit stakeholders to acquire $400 million in new debt and obtain 19% of Frontier's stock.