If you or a member of your Cocoon 'Household' has deleted the app from your smartphone you have severed the secure link to your Cocoon.
If you are the only user
Being the only user means you'll have to undertake a factory reset on your Cocoon and the instructions can be found - Here
If there are other Cocoon users
Other members of the 'Household' can invite you back to the existing Cocoon setup by going to the 'Your Cocoon' section of the app.
Please note, if you deleted the Cocoon app from your smartphone whilst at home, your Cocoon will continue to believe you are located at that location for 72 hours before it automatically sets you as Away.