As SPM compatible to Pega 7 is not available and hence there is no direct path for upgrade. You have to analyse what features of SPM is used in the application and what are your future requirements for the same. SA-HC is enhanced version of SPM containing to many new features which might be useful in future. But at the same time, you have to rebuild your application using SA-HC application.
There are other options as well which can be explored as workaround , Please contact GCS/ECS or Pega PS team for the same.