Is it good strategy to send last minute lease extensions?

[Travis Reed]

I am managing 3 commercial office tenants all with 2 year leases.  I'm not sure if this is considered "good business" but I was thinking of sending them their new updated lease/extension about 1-2 weeks prior to the end of their current lease. 1-2 weeks is not enough time for them to find a new place if they wanted to move. 

I guess my overall question is that it does not seem to be the landlord's responsibility to remind the tenant that their lease is about to expire so that they have adequite time to relocate if they were wanting to do so. 

Any thoughts on this or have better strategies? I want my tenants to of course stay as long as possible.