You could use a filter that check if the number of days since the day the reminder tiddler was created is a multiple of the time span you want, and if it is, display a checkbox in a tiddler called “repeating reminders” or anywhere else.
Something like this:
\define days_ago() [{!!created}format:date[TIMESTAMP]subtract<now TIMESTAMP>divide[86400000]floor[]add[1]multiply[-1]]
* task name: <$edit field="task-name"/>
* starting date: <$edit type="date" field="task-date"/>
* repeat each <$edit type="number" field="task-repeat"/> day(s)
<$button>
<$action-createtiddler $basetitle={{!!task-name}} created={{{ [{!!task-date}split[-]] 000000000 +[join[]] }}} remind_after_days={{!!task-repeat}}/>
<$action-setmultiplefields $fields="[{!!title}fields[]prefix[task-]]"/>
create repeating task
</$button>
;All repeating tasks
<ul>
<$list filter="[has[remind_after_days]]">
<li>
{{||$:/core/ui/Buttons/delete}} Started <$text text={{{ [subfilter<days_ago>] }}}/> days ago: <$link/>, repeat every <$edit-text type="number" field="remind_after_days"/> day(s)
</li>
</$list>
</ul>
;Tasks for today
;Todo
<ul>
<$list filter="
[has[remind_after_days]]
:filter[subfilter<days_ago>remainder{!!remind_after_days}match[0]]
:filter[getindex<now YYYY0MM0DD>else[]!match[done]]
">
<li><$checkbox index=<<now YYYY0MM0DD>> checked="done"/> <$link/></li>
</$list>
</ul>
;Done
<ul>
<$list filter="
[has[remind_after_days]]
:filter[subfilter<days_ago>remainder{!!remind_after_days}match[0]]
:filter[getindex<now YYYY0MM0DD>else[]match[done]]
">
<li><$checkbox index=<<now YYYY0MM0DD>> checked="done"/> <$link/></li>
</$list>
</ul>
Demo: repeating tasks
But this will get complex if you want to take into account the length of the month…