If I understood your question. You want to add value to the time. EX. The Global Variable %TIME now is 08.15, you want to make it 09.25.
In this case: just do the following:
Time Add (183)
A1: Variable Set [ Name:%mytime To:%TIMES+4500 Do Maths:On Append:Off ]
A2: Variable Convert [ Name:%mytime Function:Seconds to Date Time Store Result In: ]
A3: Variable Split [ Name:%mytime Splitter: Delete Base:Off ]
A4: Flash [ Text:%mytime(2) Long:Off ]