Yes. You can create a list of all your leads in LeadSquared. Navigate to Dashboard > Leads > Manage Lists. Click on Create New List. Select the following criteria to create a list of all leads- Created On, Later Than and a Date on which you created your LeadSquared account.
The image below would illustrate the process of creating a list of all leads assuming that the account was created on January 1st 2013.
Save the list as a Dynamic List so that at any point of time, you will find all the leads present in your LeadSquared account.