Append data from xls in BO Cloud

I'm trying to append (or delete and extend) data in my model. Obvisoulsy there are new dimension entries in certain dimension these are now rejected as they cannot be mapped. How do i resolve this? The entries are required..

Please note that you have data outside of 2015-04-01 and 2015-09-01. This data will not be shown in stories. Rows with data quality issues will be dropped. The following issues remain: Unmatched value(s) in 2 column(s)