SQL Server query to get the data from previous month if the column value is not present in next month

I have a table that contains a number of menu items in restaurants with respect to each month. and the table gets updated whenever there is a change in the number of items.

I want to change the table or make a new table to get the value of items for each month.

For example. If latest month is April

I want the new table to have the above rows plus the missing months with same data as last month

Thanks for the help guys appreciated

This answers the original version of the question.

Assuming that month is stored as a date with the first first day of the month, then a simple method uses recursive CTEs:

with cte as (
      select restaurant, num_items, month,
             dateadd(month, -1,
                     coalesce(lead(month) over (partition by restaurant order by month),
                              max(month) over ()
                             )
                    ) as end_month
      from t
      union all
      select restaurant, num_items, dateadd(month, 1, month), end_month
      from cte
      where month < end_month
     )
select *
from cte
order by restaurant, month;

Here is a db<>fiddle.