By Tony Owusu Frontier is asking Spirit for more time to make the case that its lower cash offer if superior to JetBlue’s offer. Frontier wants more time before the final bell rings. The past few months have seen a whirlwind of activity as Frontier Group (ULCC) – Get Frontier Group Holdings Inc. Report tries to complete a merger with fellow budget carrier Spirit Airlines (SAVE) – Get Spirit Airlines Inc. Report. That tie-up appeared set to go before JetBlue (JBLU) – Get JetBlue Airways Corporation Report decided to jump into the fray. Late last month, JetBlue boosted its cash offer for Spirit …