In order to reactivate a lease, the lease must have been closed.
To reactivate a lease:
Open a lease. For more information on how to do so, see section 4.6. or 6.1.
Go to the lease card (see image below).
Click the tab called "Dates" (see image below). Within the tab called "Dates" you will, among other things, find a field called "Closed".
Click the field "Closed" (see the first image below). When you do so, a window called "Closed" will open (see the second image below).
Go to the window called "Closed".
Specify whether or not the sub-leases connected to the lease you are working with should be reactivated when the lease you are working with is reactivated by selecting "Yes" or "No" below the following question: "Do you wish to reactivate sub-leases connected to this lease?" (see image below). Note that this can only be done if the lease you are working with has one or more sub-leases connected to it. If it hasn't you can skip this step and go straight to step 7.
Click "Reactivate the lease" (see the first image below). When you do so, you will be redirected back to the lease card where you will see that the lease you are working with has been reactivated (see the second image below).