I would like to know if I change the no of days in publication properties in General tab "Subscription expire and may be dropped if not synchronized in the following number of days. Replication meta data is kept for this amount of time". Will the subscription be reinitialised?
If so how can I avoid reinitialising the subscriber when I change the number of days?
Changing that will not reinitialize the subscriptions. If your replication is currently broken for some reason though and you change that value to be a shorter duration than how long it has been broken then your subscription(s) will be dropped.