Add 1 to a number from the worksheet before it

Hello Excel Guru's

I have 3 Tabs (will be more – once I get some help with a workable formula) - Feb, Mar and April

On the Feb tab you will see 5 columns with number shift rotations

On the Mar tab I want to refer to the Feb Tab same column and add 1 to the rotation number.

I can do this by simplifying pointing back to the Feb sheet and then do a + 1.
But the problem is when I get to 30 and it adds 1 it goes to 31 which is not a shift rotation.

I have highlighted on the Feb tab see test workbook what is happening when I use the simple + 1
How can I get the same result every time I refer back to the previous sheet but having the 31 be 6

The Apr tab refers back to the Mar tab.
The Mar tab shows the desired output I am looking for

Long Story short .. each tab will refer the previous and Add 1 to the number except for if the cell is referring to 30 I need it to go back to 6.

Let me know if you have any questions and Thanks in advance.

Thank You. Suspected an IF statement was going to be needed just could not figure it out myself. Now that I see it I understand it.

Thanks for the quick reply's you guys never fail to amaze me.