Changing dates in excel based project plan

Hello everyone

I am a complete newbie so I apologise for basic phrasing. So, here's my problem which I hope you can help me solve quicker than having to do this manually (FYI - I have just a standard excel package, no extra fancy functions referred to in other posts).

Last year I created a project plan in excel for a specific project (yes, I know this is not the best software to do this in, but users of the project plan were not keen on anything 'proper')... I am now looking to replicate this project plan for a new project, same tasks deliverables etc, but I need to change the start and end dates and would rather not do that manually for each cell. Is there a way I can do this quickly in excel via a formula. I simply need to have dates for this new project 12 months later. My dates are entered in a simple date format, nothing fancy.

Many thanks for all your help!