The HRPLimittableRelationship table was moved to multiple tables
- HRPApprovedLimit
- HRPApprovedLimitAmount
If you want more details about the process of how this was changed, look at the data upgrade scripts on msdn: http://msdn.microsoft.com/EN-US/library/jj737032.aspx
This TechNet article describes the actual creation of signing limits, in case you need it for testing. http://technet.microsoft.com/en-us/library/hh271654.aspx
Taking a shot in the dark on getting the information you wanted, there is a class called PurchReqDocument with a static method of spendingLimitStatic, where you supply the worker recid and currency code.