Current tenants staying with rent increase - Security deposit?

[Brennan Vaughn]

Just acquired a 8 unit. 7/8 tenants are staying with a 15 to 20% rent increase per door. New leases will be filled out. Should I have the tenants drop another security deposit for the new 1 year lease agreements even though some of them have been there for 2+ years? 

*Security deposits were deducted at closing so we don't have their current security deposit.

Thanks for the advice