You can add seasonal rates to the reservation plugin. To do so, follow these steps.
Go to Admin in the main menu.
Select Rental Rate Rule under Rates Configuration in the admin panel.
Click on Add Rate Rule. In the window that pops up, enter a rate rule name, select the rate name which is already added out of the available rates, Select the start date and end date from the condition drop down menu.
Then select the relevant date range of the season. and make sure tick the online checkbox in order to this seasonal rate to be reflected in the reservation plugin.
Click save button.