We just added a new update to the Lease Settings screen which will allow you to adjust the rent (actually any kind of fee or payment) up or down from a specific date going forward.
We already had a feature where you can adjust a specific receivable/payment by editing it from the Lease Settings --> Payment Schedule tab, or the Rent Roll screen - this meant you could modify the amount due or date due of a single payment. You could also delete a payment that is due as well in this manner.
What this new feature means is that you can now make a change from a date forward and apply that change to all of the subsequent due dates from that point on - this is helpful when you want to increase a tenant's rent (or decrease) part way through the lease.
The new feature is really simple to use - it lives on the Lease Settings --> Payment Schedule tab:

Hover over the row/item that represents the date/fee you want to adjust going forward, as you do so you'll see the "go-forward" icon appear for that row:

Click the icon/button and the "Adjust Amount Going Forward" popup appears:

Specify the new amount of from June 1 going forward (i.e. for the June 1 item and all rent after June 1). Note that the amount you set is not the amount you are increasing or decreasing - it's the new, full amount that will be now due.
Click "Apply Adjustment" and your changes are finalized - you'll see now that on the Rent Roll screens and reports, and in the Collect Payment screen, that the new amount is expected for the date range you have selected.