yes of course! There is several ways to do it. One is that, you can include a timerange picker, and then remove your earliest=2/1/2015:0:0:0 latest=3/1/2015:0:0:0 in your searchString, set the earliest and latest time of your timerange, and then set the earliest and latest time of your search query. Here is an example:
<form >
<label>compare a Table values </label>
<fieldset submitButton="false" autoRun="true">
<input type="time" token="time" searchWhenChanged="true">
<label/>
<default>
<earliestTime>-1d</earliestTime>
<latestTime>now</latestTime>
</default>
</input>
</fieldset>
<row>
<table >
<title >Table of Count Sourcetypes Between $time.earliest$ and $time.latest$ for index= $index$ </title>
<searchString>index=$_internal | stats count as total_count by sourcetype</searchString>
<earliestTime>$time.earliest$</earliestTime>
<latestTime>$time.latest$</latestTime>
<option name="drilldown">none</option>
<option name="field">count</option>
</table>
</row>
</form>
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