Spirit Airlines  (SAVE) , whose recent string of quarterly losses and its blocked merger with JetBlue Airways  (JBLU)  has led some to float bankruptcy rumors that are categorically rejected by the airline, has been on a reinvention course that includes major changes to its network.

Most recently, this means the canceling or suspending more than 30 routes across the country. Boston’s Logan International Airport (BOS) is by far the hardest-hit; the cut flights include service to the city from Charlotte; Chicago’s O’Hare; Columbus, Ohio; Houston, Kansas City and Pittsburgh. The city is also losing service to Norfolk, Va., and Nashville.

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Spirit is additionally cutting service to Dallas from Philadelphia, Kansas City and Milwaukee, among others.

Spirit updates schedule to ‘focus on strongest-performing routes’

All these flights will be phased out throughout October and November while some, such as the Boston-Chicago route, will continue running into December. Flights between Dallas and Kansas City, Memphis and Philadelphia have already been pulled out of service.

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“We routinely evaluate our network and make adjustments to support the company’s business strategy based on current market and operating conditions,” a Spirit spokesperson said in a press statement. “As part of this process, we updated our upcoming schedule to focus on our strongest performing routes.”

Other flight cuts include service between Charleston International Airport (CHS) and Metropolitan Wayne County Airport (DTW) in Detroit as well as LaGuardia Airport (LGA) in New York as well as routes between Las Vegas’s Harry Reid International Airport (LAS) and St. Louis and Minneapolis–St. Paul.

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Booked on these Spirit routes? These are your options

The primary reason for the cancellations comes down to lack of the traffic that would make running such routes profitable. Competition for those flights has increased from American Airlines  (AAL) , Delta Air Lines  (DAL)  and JetBlue.  (JBLU)  

Boston in particular is a strategic city for JetBlue, which built its flight network out of the Northeast.

The spokesperson further said that those who have already booked travel on those routes will be “notified of their options.” Travelers who have not yet received or do not want to wait for an email from the airline can also reach out to the airline directly for a choice of either a full refund or rebooking on a different flight.

This can also be done by logging in with the confirmation code for the canceled flight. 

The extensive cuts mean that Spirit’s capacity has been reduced by as much as 17% during the autumn. The airline did say that some of the Boston routes may be brought back next year during the peak summer travel period.

Other recent cuts made by the airline include axing international flights out of Houston back in May, as well as cutting certain routes between Fort Lauderdale and Los Angeles, Miami and Atlanta and between Puerto Rico’s San Juan and several Florida cities.

Other changes at Spirit include introducing four different fare classes.

“What we’ve seen over time is that less people are actually flying on Spirit,” Chief Commercial Officer Matt Klein said during a CBS interview in July. “So we believe the changes we’re making are about attracting new customers.”