How to capture and post up-to-date accrual balance liability (in dollars) and record the amount for

Example: the employee was hired at the rate of $10/hour but is now earning $15/hour.  The employee has accrued vacation time of 10 hours.  The liability at the moment should reflect $150, not $100.  How would we go about systematically generating the payroll entry of the additional $50 and post the amount as the company's liability?  (the preference is to have this adjustment done as of each pay cycle not having to manually create the GL entries)