Well, yes, by the same way you increase the value in the first place. Just reset it to 0 in <trial pause> as in
<trial pause>
/ ontrialend = [values.numberoftrialsrun=0]
[...]
</trial>
Alternatively change your /branch to also trigger for 208, 312, etc. I.e.,
/ branch = [if (values.numberoftrialsrun == 104 || values.numberoftrialsrun == 208 || ...) trial.pause]
Regards,
~Dave