Since this variation is in triplets, the challenge for the spiccato bow-stroke is to cross from the E-string to the A-string on a down bow for beats 1 and 3 and then on an up bow for beats 2 and 4. To begin with, practice the string crossing pattern détaché in the middle of the bow.
Make sure that your base knuckles in the bow hand are flexible and that they give slightly when changing to a down bow, whether you are crossing on an up bow or a down bow.
To help with a clear even spiccato stroke, try using the side of the hair and keep the bow close to the string.
Practice in rhythm the upper line on its own to hear the melodic line clearly (just the E string notes for bars 1 and 2, just the A string notes for bar 3 and so on).
Make sure that the left hand is ready. For example in bar 1 the 3rd finger A needs to be down before the 4th finger lifts. Take care after crossing strings to have your fingers calmly in place on the new string before the bow begins the stroke. For example in the first beat of bar 2 the 2nd finger needs to be ready.
Practise the left-hand patterns firstly as double stops and then placing your fingers one note ahead.