As Bernie pointed out, remove the NC T15 in the first line. TMRAs are not reset that way. Also, I'm assuming that you are using a K value of 3600 for the TMRA and not 360.
You don't need the C152 one-shot either. You can use the T15 output to do the addition. Also, try placing the logic that does the addition before the TMRA. This works because the T15's output is not reset at the end of the scan, it is reset when the T15's instruction is reevaluated.
Personally, I would just use a counter to keep track of the ETM value instead of doing the addition logic you have. Using a counter will place the logic to increment and reset the ETM value in one rung. If you need to keep track of a value larger than 9999 (the largest value a CNT will keep track of) use an Up Down Counter, it keeps track of a value up to 99999999.